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Limited information exists regarding the epidemiology, metastasis, and survival of dermatofibrosarcoma protuberans (DFSP). To measure DFSP incidence and assess metastasis and survival outcomes. Incidence rate, overall and DFSP-specific survival outcomes for primary DFSP tumors contained in the Surveillance, Epidemiology, and End Results (SEER) registry were analyzed via quasi-Poisson regression, Cox, and competing risk analyses. DFSP incidence rate was 6.25 (95% CI, 5.93-6.57) cases per million person-years with significantly higher incidence observed among Black individuals than White individuals (8.74 vs 4.53). DFSP with larger tumor size (≥3 cm, odds ratio [OR]: 2.24; 95% CI, 1.62-3.12; P <.001) and tumors located on the head and neck (OR: 4.88; 95% CI, 3.31-7.18; P <.001), and genitalia (OR: 3.16; 95% CI, 1.17-8.52; P =.023) were associated with significantly increased risk of metastasis whereas higher socioeconomic status was associated with significantly decreased risk of metastasis. Larger tumor size (≥3 cm), regardless of location, and age (≥60 years) were associated with significantly worse overall and cancer-specific survival. Retrospective design of SEER. DFSP incidence is 2-fold higher among Black than White individuals. The risk of DFSP metastasis is significantly increased with tumor size ≥3 cm and tumors located on head and neck, and genitalia. Larger tumor size (≥ 3 cm), regardless of location, and age (≥60 years) are the most important prognostic indicators of survival. [ABSTRACT FROM AUTHOR]

Aims: The majority of dermatofibrosarcoma protuberans (DFSP) harbour PDGFB or PDGFD rearrangements. We encountered ALK expression/rearrangement in a PDGFB/D‐negative CD34‐positive spindle cell neoplasm with features similar to DFSP, prompting evaluation of ALK‐rearrangements in DFSP and plaque‐like CD34‐positive dermal fibroma (P‐LDF). Methods and Results: We searched the archives of academic institutions for cases previously coded as DFSP and P‐LDF. NGS‐naïve or PDGFB‐negative DFSP were screened for ALK (clone D5F3) expression by immunohistochemistry. NGS or ALK FISH was performed on ALK‐positive cases. Methylome profiling studies were performed and compared with conventional DFSP. One case of "DFSP" and two "P‐LDF" with ALK expression were identified from the archives, while four cases were detected prospectively. These seven cases (6F:1M; 8 months to 76 years) arose in the dermis of the arm (two), scalp, eyelid, thigh, abdomen, and shoulder and ranged from 0.4 to 4.2 cm. Tumours were composed of spindled cells and displayed a storiform growth pattern. Cytologic atypia was absent, and mitotic figures were scarce (0–2/10 HPFs, high power fields). The lesional cells were diffusely positive for CD34 and ALK and negative for S100 protein. By NGS (n = 5), ALK fusion partners included DCTN1 (2), PLEKHH2, and CLIP2 in DFSP‐like cases and FLNA in P‐LDF‐like lesions. ALK FISH was positive in one (of two) cases previously labelled P‐LDF. Methylome profiling of two (of three) ALK‐rearranged DFSP‐like tumours showed clustering with conventional DFSP in the UMAP dimension reduction plot. To date, no tumour has recurred (n = 2; 26, 27 months). Conclusion: We describe a cohort of novel ALK‐rearranged tumours with morphologic features similar to DFSP. [ABSTRACT FROM AUTHOR]

Simple Summary: Skin cancer is a major global problem, and over the last decade, ultrasound technology has advanced significantly, enhancing our ability to detect and identify the most common types of skin cancer, including both the primary tumor and its locoregional metastases. Background: Skin cancer is the most common cancer in human beings. Ultrasound is a powerful and non-invasive imaging technique that has expanded its use in dermatology, including in the skin cancer field. The full range of critical anatomical information provided by ultrasound cannot be deduced from a naked eye examination, palpation, or other imaging techniques such as dermoscopy, confocal microscopy, magnetic resonance imaging, or PET-CT (Positron Emission Tomography-Computed Tomography). Methods: This review practically analyzes the main ultrasonographic features of the most common types of skin cancers and the performance of the locoregional staging according to the literature, which is illustrated by state-of-the-art clinical and ultrasonographic correlations. Results: The most common types of skin cancer show recognizable ultrasonographic patterns. Conclusions: Among the current radiological imaging techniques, ultrasound has the highest axial spatial resolution. Compared to other imaging techniques used in dermatology, it shows the great advantage of penetrating the soft tissues thoroughly, which allows us to detect and identify the most common skin types of skin cancer, including both the primary tumor and its locoregional metastases. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue sarcoma characterized by an asymmetric, infiltrative growth pattern and a high risk of local recurrence. This study aims to evaluate the effectiveness of various imaging modalities in the assessment and management of DFSP. Nine imaging modalities were reviewed including: Ultrasound (US), High‐Frequency Doppler Ultrasound (HFUS), Computed tomography (CT), Positron emission tomography–computed tomography (PET‐CT), and Magnetic Resonance Imaging (MRI), High‐resolution‐MRI (HR‐MRI), Magnetic Resonance Spectroscopy (MRS), Optical Coherence Tomography (OCT), and Dermatoscopy. Imaging is mainly used for preoperative assessment and surgical planning, not routine diagnosis. US is effective for initial evaluations, demonstrating superior ability in detecting muscle invasion and defining tumour boundaries (sensitivity – 81.8%, specificity – 100%). MRI is valuable for preoperative evaluation, surgical planning, and monitoring DFSP recurrence. It more accurately assesses tumour depth than palpation, with a sensitivity of 67% and specificity of 100%, but was inferior when compared to US. CT is utilized in cases of suspected bone involvement or pulmonary metastasis. For advanced or recurrent DFSP, PET‐CT helps manage treatment responses and imatinib therapy. Emerging technologies like MRS and OCT show potential in improving diagnostic accuracy and defining surgical margins, though more data are needed. US, MRI, and CT are the primary imaging modalities for DFSP. Emerging technologies like HR‐MRI, PET‐CT, MRS, and OCT hold promise for refining diagnostic and management strategies. Integrating multiple technologies could enhance management, particularly in atypical or aggressive cases. Further studies are required to refine imaging protocols and improve DFSP outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: Dermatofibrosarcoma protuberans (DFSP) is a rare proliferative condition representing skin sarcomas which is known to locally recur yet very rarely metastasizes. Its genetic background is a reciprocal translocation t(17;22)(q22;q13) that produces COL1A1-PDGFB gene fusion. Complete resection is the primary treatment. The aim of this reappraisal is to review various correlates of the condition. Our review underlines that cases of low-to-moderate grade DFSP with excellent prognosis must be distinguished from high grade fibrosarcomatous DFSP with a much worse prognosis. Dermatofibrosarcoma protuberans (DFSP) is a rare proliferative condition representing skin sarcomas which is known to locally recur yet very rarely metastasizes. Its genetic background is a reciprocal translocation t(17;22)(q22;q13) that produces COL1A1-PDGFB gene fusion. Complete resection is the primary treatment. The aim of this review is to outline the pathogenesis, diagnosis, and management of DFSP. A clear-cut distinction between low-to-moderate-grade DFSP with excellent prognosis and high-grade fibrosarcomatous DFSP with a much worse prognosis is underlined. Malignant transformation within DFSP (or high histologic grade), older age, being female, large primary tumor size (≥10 cm), narrow surgical margins of excision (<3 cm), surgical margin positivity for tumor cells, short time to recurrence, numerous recurrences, tumor that was recently rapidly enlarging, and presence of pain in the tumor have all been proposed as clinicopathological risk factors for recurrence and metastasis. A tendency for local growth and local relapses of well- and moderately differentiated DFSPs is an argument for their surgical excision, possibly combined with reconstructive surgery, even in patients of advanced age. Another main point of this review is that cases of DFSP with fibrosarcomatous transformation are a challenge and require careful medical attention. Both anatomopathological evaluation of the presence of lymphovascular space invasion and sentinel lymph node biopsy at DFSP surgery merit further study. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a superficial sarcoma characterized by infiltrative growth with tentacle-like borders. Mohs micrographic surgery (MMS) is the preferred treatment option for DFSP. However, the imprecise boundary localization in MMS leads to an increased number of Mohs layers required and a longer surgery time. High-frequency ultrasound has excellent tissue recognition capability for DFSP, allowing for precise boundary marking. In this study, we retrospectively analyzed 14 cases of DFSP treated with MMS using preoperative ultrasound localization and three-dimensional reconstruction at Xiangya Hospital over the past 5 years. We also reviewed previous studies on MMS for DFSP treatment. It was found that the average number of Mohs layers for patients after preoperative ultrasound localization was 1.57, ranging from 1 to 3, which was less than the previously reported 1.86 layers, ranging from 1 to 12. This effectively reduced the number of Mohs layers required. By utilizing preoperative high-frequency ultrasound to determine the boundaries and depth of DFSP, the number of Mohs layers can be effectively reduced, leading to less workload for pathological examination, shorter operation time, and reduced surgical risks for patients. Ultrasound imaging data can be used for three-dimensional reconstruction, enabling less experienced Mohs surgeons to have a visual understanding of the morphology and extent of infiltration of the lesions. This aids in developing optimal surgical plans, smoothing the learning curve, and promoting the wider adoption of MMS. [ABSTRACT FROM AUTHOR]

Cutaneous dermatofibrosarcoma protuberans (DFSP) is a fibrohistiocytic tumor characterized by a high risk of local recurrence but a low risk of metastasis. Wide local excision (WLE) has been an important treatment option, but its clinical outcomes and safety have not been thoroughly evaluated in previous reports. The aim of this study was to determine appropriate surgical margins (deep and lateral) and prognostic factors associated with recurrence‐free survival (RFS) of DFSP. A database collected by two dermatology departments in Japan was retrospectively reviewed to identify 116 patients with DFSP who underwent complete resection with WLE between 1994 and 2021. Sixty‐one men (53%) and 55 women (47%) were included in our cohort. The primary sites of DFSP were as follows: 11 head and neck (9%); seven face (7%); 12 upper extremities (10%); 20 lower extremities (17%); and 66 trunk (57%). There were 103 cases (89%) of primary DFSP and 13 cases (11%) of recurrent DFSP. Total 10‐year RFS was 96.6%. There were significant differences in RFS by tumor size (median size: 3 cm), disease status (primary versus recurrent DFSP), and fibrosarcomatous change (positive versus negative) (all p < 0.05). Two patients (1.7%) with buccal or head lesions had positive deep margins. In all cases, the lateral margin was negative at the postoperative evaluation. Tumor size, disease status, and fibrosarcomatous change are important risk factors for recurrence. Both face and head–neck lesions were more likely to have positive deep margins than other anatomic areas in DFSP. Although this study was limited by its retrospective design, a narrow 2‐cm lateral margin is especially considered for low‐risk patients. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFS) is a mesenchymal-origin skin tumor with intermediate malignancy. Though rare, it's not exceptional, comprising about 0.1% of malignant skin tumors.The authors discuss clinical, radiological, histopathological studies, and various therapeutic modalities for this tumor.Our 82-year-old patient presented with a 3 cm swelling on the right arm, initially undergoing biopsy followed by surgical excision of the mass.Adjuvant treatment with radiotherapy or chemotherapy is unnecessary unless recurrence or malignant transformation occurs. Histological analysis is crucial for diagnosis. The preferred treatment method is wide surgical excision.Prognosis primarily depends on malignancy, especially at the local level, with a high risk of recurrence. It's rare for a distinctly malignant sarcomatous transformation with metastasis to occur.

Dermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive cutaneous sarcoma with a propensity for recurrence. Its management, particularly in the head and neck (H&N) region, presents unique challenges. This study aimed to evaluate the effectiveness of Mohs micrographic surgery (MMS) compared to wide local excision (WLE) in treating H&N DFSP and its impact on recurrence rates and tissue preservation. A comprehensive search was conducted in PubMed/MEDLINE, yielding 29 relevant studies. We included studies comparing MMS and WLE in adult patients with H&N DFSP and reporting local recurrence outcomes. Data were analyzed using random effects analysis, with a meta-analysis performed for comparative studies. Analysis of studies demonstrated a lower recurrence for MMS. Comparative analysis of five studies involving 117 patients showed a significantly lower recurrence rate in the MMS group (2%) compared to the WLE group (19%). Margin status varied between studies, with some achieving negative margins at shorter distances. In the management of H&N DFSP, MMS has emerged as a superior surgical technique, consistently associated with reduced recurrence rates and the potential for tissue preservation. The adoption of MMS should be considered for its capacity to achieve negative margins with fewer processing steps, particularly in anatomically complex regions like the H&N. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is an uncommon soft tissue tumor involving the dermis and subcutaneous fat that rarely occurs in children, manifested as a slowly growing firm plaque on the trunk. A 12-year-old girl patient presented with dark patch on the nasal root after finishing 25 sessions of radiotherapy. Initially, patient came to Oncology Surgery Clinic at Hasan Sadikin General Hospital Bandung with the chief complaint of a large exophytic mass located in the nasal area, which was neither itchy nor painful. A large, firm, painless mass with no sign of localized heat or redness was found on physical examination. There were no palpable cervical or axillary lymph nodes. Wide local excision and frontal flap procedure were performed by Oncology Surgery Department leaving a pedicle with 2× 1.5× 1 cm on size was observed. Upon histopathological examination, tumor mass was found in the subepithelium and consisted of oval to spindle-shaped cells that were hyperplastic, compacted, diffuse, forming fasciculus, whorled, and cartwheel. Cell nuclei were pleomorphic (oval to wavy), hyperchromatic, with clear nucleolus, and occasion mitotic figures. Hyalinisation was seen between the tumor masses. On immunohistochemical stains, there were diffuse positivity for epithelial membrane antigen (EMA) and vimentin. Based on the histological and immunohistochemical findings, the diagnosis of stage II DFSP was made. Until now, there is no established algorithm for treatment of DFSP. Wide local excision and radiotherapy for 25 sessions was performed on this patient, resulting in complete tumor mass removal. After three months of observation, the second surgery was done to remove a pedicle; however, there is no recurrence of tumor growth. Despite its rarity, DFSP should be considered as a differential diagnosis to avoid underdiagnosis or misdiagnosis. [ABSTRACT FROM AUTHOR]

Fibroblastic connective tissue nevus (FCTN) is a rare, benign dermal mesenchymal lesion of fibroblastic and myofibroblastic lineage. We report a case of a 2‐year‐old male who presented with an 18‐month history of an erythematous, asymptomatic, unchanging dermal plaque on the right medial frontal scalp. A punch biopsy showed a disorderly, bland, dermal fibroblastic spindle cell proliferation extending to the superficial subcutis. It stained positive for CD34, and concern for dermatofibrosarcoma protuberans was raised. However, FISH was negative for PDGFB rearrangement, and the constellation of findings was most consistent with FCTN. This case underscores the importance of distinguishing CD34+ mesenchymal tumors for both dermatologists and dermatopathologists. As these represent a rather diverse group of lesions with different biological behaviors, a knowledge of the differential diagnosis of these entities is critical for proper patient management. [ABSTRACT FROM AUTHOR]

Background Dermatofibrosarcoma protuberans (DFSP) is one of the most challenging cutaneous cancers in surgical clinic practice. Excision with negative margins is essential for effective disease control. However, wide surgical margins and maximal tissue conservation are mutually exclusive. Mohs micrographic surgery conserves tissue but is time-consuming. Thus, we developed a novel specimen radiography system that can be used intraoperatively. Aims To introduce a specimen radiography system for evaluating intraoperative surgical margins in patients with dermatofibrosarcoma protuberans. Methods Since September 2017, we have treated seven biopsy-proven cases of local DFSPs via local excision with surgical margins of 2–4 cm. During operations, the operative specimens were screened using the specimen radiography system. All surgical specimens were pathologically examined intraoperatively. Results Five patients were men and two were women, of median age 36 years. The mean radiographic screening time was 9.7 ± 2.3 min. Radiographically negative margins were confirmed intraoperatively. The minimal margin width ranged from 5.0 to 35.4 mm (mean width 16.9 ± 10.4 mm). The intraoperatively negative radiographic margins were consistent with those revealed by postoperative pathology. The minimal pathological margin width ranged from 4.0 to 34.5 mm (mean 16.6 ± 10.1 mm) and was not significantly different from the intraoperative data. Limitations The sample size was small and positive or negative predictive values were not calculated. Conclusions We introduce a novel method of intraoperative surgical margin assessment for DFSP patients. It may find broad clinical and research applications during oncoplastic surgery. [ABSTRACT FROM AUTHOR]

Simple Summary: While sun exposure and associated tissue changes stemming from ultraviolet radiation are closely associated with the most common forms of skin cancer, far less is known regarding rare types of skin cancer. In this study, for the first time, we used a light microscopy technique to evaluate connective tissue changes in samples from patients with six different types of rare skin cancers, assessing the relationship between these changes, patient age, and whether tumors arose on sun-exposed parts of the body. We found that these tissue changes were most pronounced for patients with specific cancers known to be linked to chronic sun damage and tumors arising on sun-exposed parts of the body. We also noted tumor type-specific trends in terms of sex ratios, sites of tumor presentation, and the relationship between the development of particular tumors and patient immunosuppression. Our results are important and novel as they expand the available data associated with these rare skin cancers while also offering insight into the value of differentiating among these tumor types based on their relationship with sun exposure, potentially informing preventative, diagnostic, and/or therapeutic approaches. (1) Background: Rare skin cancers include epithelial, neuroendocrine, and hematopoietic neoplasias as well as cutaneous sarcomas. Ultraviolet (UV) radiation and sunburns are important drivers for the incidence of certain cutaneous sarcomas; however, the pathogenetic role of UV light is less clear in rare skin cancers compared to keratinocyte cancer and melanoma. In this study, we compared the degree of actinic elastosis (AE) as a surrogate for lifetime UV exposure among selected rare skin cancers (atypical fibroxanthoma [AFX], pleomorphic dermal sarcoma [PDS], dermatofibrosarcoma protuberans [DFSP], Kaposi sarcoma [KS], Merkel cell carcinoma [MCC], and leiomyosarcoma [LMS]) while taking into account relevant clinical variables (age, sex, and body site). (2) Methods: We newly established a semi-quantitative score for the degree of AE ranging from 0 = none to 3 = total loss of elastic fibers (basophilic degeneration) and multiplied it by the perilesional vertical extent (depth), measured histometrically (tumor-associated elastosis grade (TEG)). We matched the TEG of n = 210 rare skin cancers from 210 patients with their clinical variables. (3) Results: TEG values were correlated with age and whether tumors arose on UV-exposed body sites. TEG values were significantly higher in AFX and PDS cases compared to all other analyzed rare skin cancer types. As expected, TEG values were low in DFSP and KS, while MCC cases exhibited intermediate TEG values. (4) Conclusions: High cumulative UV exposure is more strongly associated with AFX/PDS and MCC than with other rare skin cancers. These important results expand the available data associated with rare skin cancers while also offering insight into the value of differentiating among these tumor types based on their relationship with sun exposure, potentially informing preventative, diagnostic and/or therapeutic approaches. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a cutaneous sarcoma with a high propensity for local invasion and recurrence. Although it is a rare event, the occurrence of multiple tumors in a single patient raises a diagnostic dilemma, as metastatic disease should be differentiated from multiple primary malignant events. In more than 90% of DFSP, a pathogenic t(17;22) translocation leads to the expression of COL1A1::PDGFB fusion transcripts. Karyotype analysis, fluorescence in situ hybridization, and RT‐PCR can be useful ancillary studies in detecting this characteristic rearrangement, and sequencing of the fusion transcript can be used to support a clonal origin in metastatic and multifocal disease. However, previous reports have demonstrated variable sensitivity of these assays, in part due to the high sequence variability of the COL1A1::PDGFB fusion. Here, we report a patient who developed two distinct DFSP tumors over the course of 7 years. Chromosomal microarray analysis identified distinctive genomic alterations in the two tumors, supporting the occurrence of multiple primary malignant events. [ABSTRACT FROM AUTHOR]

The article explores racial disparities in dermatofibrosarcoma protuberans (DFSP) patients in the United States, with Black patients facing a higher risk of disease-specific mortality and larger tumor sizes compared to White patients. Using the SEER database, the study found that non-White patients, particularly Black individuals, presented with tumors located on the trunk and required more radiation therapy. Multivariate analysis revealed that identifying as Black independently increased the risk of disease-specific mortality. The study emphasizes the need for improved screening and prevention strategies for DFSP in populations of color, especially Black patients, to address the observed poorer survival outcomes. [Extracted from the article]

Dermatofibrosarcoma Protuberans (DFSP) is a rare soft tissue sarcoma distinguished by its infiltrative growth pattern and recurrence potential. Understanding the molecular characteristics of DFSP is essential for enhancing its diagnosis, prognosis, and treatment strategies. The paper provides an overview of DFSP, highlighting the significance of its molecular understanding. The gene expression profiling has uncovered unique molecular signatures in DFSP, highlighting its heterogeneity and potential therapeutic targets. The Platelet-Derived Growth Factor Receptors (PDGFRs) and Fibroblast Growth Factor Receptors (FGFRs) signaling pathways play essential roles in the progression and development of DFSP. The abnormal activation of these pathways presents opportunities for therapeutic interventions. Several emerging therapies, i.e., immunotherapies, immunomodulatory strategies, and immune checkpoint inhibitors, offer promising alternatives to surgical resection. In DFSP management, combination strategies, including rational combination therapies, aim to exploit the synergistic effects and overcome resistance. The article consisting future perspectives and challenges includes the discovery of prognostic and predictive biomarkers to improve risk stratification and treatment selection. Preclinical models, such as Patient-derived xenografts (PDX) and genetically engineered mouse models, help study the biology of DFSP and evaluate therapeutic interventions. The manuscript also covers small-molecule inhibitors, clinical trials, immune checkpoint inhibitors for DFSP treatment, combination therapies, rational therapies, and resistance mechanisms, which are unique and not broadly covered in recent pieces of literature.

AbstractDermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive cutaneous sarcoma with a propensity for recurrence. Its management, particularly in the head and neck (H&N) region, presents unique challenges. This study aimed to evaluate the effectiveness of Mohs micrographic surgery (MMS) compared to wide local excision (WLE) in treating H&N DFSP and its impact on recurrence rates and tissue preservation. A comprehensive search was conducted in PubMed/MEDLINE, yielding 29 relevant studies. We included studies comparing MMS and WLE in adult patients with H&N DFSP and reporting local recurrence outcomes. Data were analyzed using random effects analysis, with a meta-analysis performed for comparative studies. Analysis of studies demonstrated a lower recurrence for MMS. Comparative analysis of five studies involving 117 patients showed a significantly lower recurrence rate in the MMS group (2%) compared to the WLE group (19%). Margin status varied between studies, with some achieving negative margins at shorter distances. In the management of H&N DFSP, MMS has emerged as a superior surgical technique, consistently associated with reduced recurrence rates and the potential for tissue preservation. The adoption of MMS should be considered for its capacity to achieve negative margins with fewer processing steps, particularly in anatomically complex regions like the H&N.

Introduction: Dermatofibrosarcoma protuberans (DFSP) is the most common sarcoma of the skin. Although distant metastases are infrequent, DFSP is highly aggressive locally with frequent local recurrences. It has been reported that the presence within the tumour of areas histopathologically mimicking fibrosarcoma may increase the risk of recurrence. Objective: The objective of this study was to review the clinical features of our patients with DFSP and the factors associated with recurrence of the tumour, focussing on the presence of fibrosarcomatous areas. Methods: Retrospective study of patients with DFSP diagnosed in 1990–2021 in a tertiary university hospital. The medical records were reviewed to obtain the following data: age, sex, tumour location, diameter, evolution time, presence of fibrosarcomatous areas, development of recurrence, and follow-up. Factors possibly associated with disease-free survival were analysed with Kaplan-Meier method and multivariate Cox regression. Results: 148 patients (74 women/74 men, mean age 46.28 years, SD 14.431) were included in the study. Tumours involved the head and neck in 15 cases, thorax in 31, abdomen in 16, upper back in 43, lower back in 10, upper extremities in 10, and lower extremities in 23. Fibrosarcoma-like areas were observed in 16 tumours (10.81%). In 17 patients (11.49%), recurrences were observed (13 local recurrences, 3 lung metastasis, and 1 local recurrence with lung metastasis). Fibrosarcomatous DFSP recurred more frequently than classic DFSP (50% vs. 6.82%, respectively), and its disease-free survival was significantly lower (p < 0.001). In multivariate Cox regression, the presence of fibrosarcomatous areas was the only factor influencing disease-free survival. Conclusions: It is important to identify the fibrosarcomatous variant since it recurs more frequently and has lower recurrence-free survival. Distant metastases, mainly in the lung, are also more frequent in fibrosarcomatous DFSP. [ABSTRACT FROM AUTHOR]

Background: Diffractive microscopy creates contrast within samples that are otherwise uniform under bright light. This technique can highlight subtle differences in refractive indices within birefringent samples containing varying amounts of mature collagen. Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) possess differences in their mature collagen content and, therefore, may be distinguishable using diffractive microscopy. Methods: Two hundred forty‐two DF and 85 DFSP hematoxylin–eosin (H&E)‐stained specimens were analyzed using diffractive microscopy. Data regarding the distribution pattern and strength of refractility was recorded. Results: DFSP was more frequently found to be focally, weakly, or non‐refractile (82.9%; n = 68) under diffractive microscopy, while DF more often showed diffusely bright refractility (52.9%; n = 128). DFSP samples with diffuse refractility in portions of the lesion (17.1%; n = 14) also exhibited a unique checkerboard pattern distinct from that which was seen in DF samples. Conclusions: The absence of diffuse refractility was more closely associated with DFSP, as was the presence of a unique checkerboard diffraction pattern. Despite high sensitivity (Sn = 82.9%), absent refractility was not a specific test (Sp = 52.9%), with 47.1% (n = 114) of DF samples sharing this feature. The distinction between DF and DFSP is often diagnosed using H&E alone. In difficult cases, examination of collagen under diffractive microscopy may be useful in distinguishing DFSP from DF and provide an alternative cost‐effective tool to immunohistochemical staining. [ABSTRACT FROM AUTHOR]

Background: Head and neck dermatofibrosarcoma protuberans (HNDFSP) is extremely rare and not entirely understood. Objective: To investigate the clinicopathological features of HNDFSP and identify the expression of its clinically relevant indicators, with the expectation of improving the existing treatment strategies. Methods: A long‐term follow‐up of patients with HNDFSP who received treatment between 2000 and 2021 at Shanghai Ninth People's Hospital was conducted. The clinical, histological, and immunohistochemical data of the patients were retrieved and analyzed. The endpoint of the study was the incidence of significant disease‐related clinical events (recurrences or metastasis). Results: A total of 49 patients with HNDFSP were included in the study, with males (92.7%) predominating than females (7.3%). Eighteen patients developed recurrent disease (36.8%) after surgery, and the median time of recurrence was 48 months (interquartile, 20–74 months). Metastasis occurred in two cases (4.1%). Two patients died during follow‐up, both with local recurrence, and one of them with intestinal metastasis. Post‐operation radiotherapy was administered to eight patients (16.3%) and the effect in local control was remarkable. Age, tumor size, and negative margins with sufficient safety width were the main independent factors affecting the disease‐free survival. Several potential targeted therapeutic indicators, including EZH2 (80.0%), EGFR (91.4%), PDGF (97.1%), PD‐L1 (77.1%), and VEGF (77.1%), were positively expressed in most tumor samples. Conclusion: HNDFSP is rare, significantly challenging to control locally, and has a worse prognosis with current treatment strategies. Wide local excision and long‐term follow‐up are needed. Radiotherapy could improve the prognosis of patients with HNDFSP. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a slow-growing, soft-tissue tumour of early or mid-adult life, affecting both the genders equally. The most common sites are soft tissue of the trunk (50 to 60%), followed by proximal extremities (20 to 30%) and the head and neck region (10 to 15%). Its metastatic potential is low though the local recurrence rate is high. Here, we report a case of a female patient with a large soft tissue growth located at the right cheek, chin and neck region. Local excision was done under the impression of a benign tumour such as lipoma or sebaceous cyst. Histological evaluation showed bland spindle cells arranged in a storiform pattern questioning the provisional diagnosis of the lesion. Further evaluation with the immunohistochemistry (IHC) panel confirmed the diagnosis of DFSP. Since it is a rare tumour of the head and neck region with non-alarming initial presentation and the potential for erroneous diagnosis as another lesion, we present a case of DFSP. [ABSTRACT FROM AUTHOR]

Background: Dermatofibrosarcoma protuberans (DFSP) is a superficial soft tissue sarcoma, and surgical excision is the first-line treatment. The aim of this systematic review is to provide an update about the current indications and clinical results regarding the use of postoperative radiotherapy in DSFP, considering both adjuvant and salvage setting. Methods: We conducted a systematic literature review using the main scientific database, including Cochrane library, Scopus, and PubMed, for any relevant article about the topic, and we considered all available papers without any time restriction. Results: Twenty-two papers, published between 1989 and 2023, were retrieved and considered eligible for inclusion in this review. Regarding the fractionation schedules, most authors reported using standard fractionation (2 Gy/die) with a wide total dose ranging from 50 to 70 Gy. The local control after postoperative radiotherapy was excellent (75–100%), with a median follow-up time of 69 months. Conclusions: After the primary surgical management of DFSP, postoperative radiotherapy may either be considered as adjuvant treatment (presence of risk factors, i.e., close margins, recurrent tumours, aggressive histological subtypes) or as salvage treatment (positive margins) and should be assessed within the frame of multidisciplinary evaluation. [ABSTRACT FROM AUTHOR]

Cutaneous fibrous histiocytoma (FH) is considered a benign dermal tumor. The cellular variant is rare and poorly documented. Besides presenting a high risk of local recurrence, it has a low but serious metastatic potential. We present a case of metastatic cellular FH and also review the literature on this tumor, given its unusual metastatic development. A 47‐year‐old male patient presented with a lesion in the anterior surface of the right thigh, which has been present since adolescence but had grown during last year. Anatomopathological evaluation revealed a cellular FH, and the lesion was completely removed. Six months later, tumor recurrence with multiple compartment muscle involvement and pulmonary metastasis were detected. Both lesions were completely resected and after 3 years of follow‐up, the patient is asymptomatic and free of the disease. We conclude that FH should be carefully sampled to detect variants with high local recurrence rates or with some metastatic risk such as the cellular one. We recommend wide surgical resection and a close follow‐up including chest x‐rays or thorax computed tomography (CT) in all cellular FH cases with local recurrence. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a rare skin tumor. There is no standard recommendation for its surgical management. The currently used histological analysis are HES (hematoxylin eosin saffron) staining and immunohistochemistry for CD34 expression in particular cases. Fluorescent in situ hybridization (FISH) technique is only used to qualify the DFSP as translocated or non-translocated and is not used as a diagnostic method. The aim of our study was to determine by FISH (as a diagnostic method) whether cancerous cells that could not be identified through HES staining ± immunohistochemistry were present at the two-centimeter margins that were found to be tumor-free. Samples from patients who underwent surgery between 2010 and 2018 were collected. Intralesional and peripheral (at 2 cm margins) paraffin slides were included. An average of 7.4 slides per specimen was analyzed. Firstly, the preselected slides were reread by a senior pathologist to confirm the absence of microscopic findings of DFSP at 2 cm margins. Secondly a FISH analysis was used as a quantitative diagnostic approach, in order to find the t(17;22) translocation. Among the seven specimens that included 2 cm margins, two samples presented one or more translocations, which were not visible in standard morphology assessments at two centimeters tumor-free margins. FISH analysis can have a new role in defining tumor-free margins. This would reduce the incidence of disease recurrence after resection and improve the post-operative complementary care. [ABSTRACT FROM AUTHOR]

Abstract is missing (Quiz)

Abstract Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant soft-tissue tumor that originates from the skin. It has a slow onset in the early stages, non-specific clinical symptoms, low specificity, and can easily be overlooked, missed, or misdiagnosed by clinicians and pathologists. In addition, DFSP is prone to recurrence after local surgical treatment; however, distant metastasis, especially abdominal metastasis, is rare, which is also a challenge for the accurate diagnosis of DFSP when it progresses distantly. Now a case of abdominal metastasis of DFSP is reported. The patient has been treated with imatinib for ten years, and the lesion has shrunk, but because the patient has been receiving imatinib treatment, his abdominal lesion was once misdiagnosed as gastrointestinal stromal tumor. Therefore, we report on this case to enhance the understanding of the diagnosis and treatment of DFSP, and to provide reference for the pathological diagnosis and precise treatment of such patients.

Introduction: Dermatofibrosarcoma protuberans (DFSP) originated as keloid sarcoma, gaining its current designation in 1925. DFSP exhibits slow growth, categorizing it as a low- to intermediate-grade malignant sarcoma. Initially presenting as a small, firm, irregular skin nodule, it undergoes sudden, rapid growth, forming a prominent mass. While locally aggressive, distant metastasis is rare. DFSP affects mainly the torso then proximal extremities. Case Presentation: In this case study, we described a 57-year-old male individual who presented with a chest midline swelling that was progressing in size. A punch biopsy showed inconclusive results. Thus, a wide local excision was carried out along with sending the initial biopsy slides to Mayo Clinic for second opinion. A diagnosis of DFSP was confirmed, which is an uncommon and locally aggressive tumor affecting soft tissues. The primary histological diagnosis relies on immunohistochemical stains, enabling the distinction between DFSP and other fibrous tumors. Conclusion: Diagnosing DFSP is challenging due to its similarity to other skin lesions. A multidisciplinary approach is vital for accurate diagnosis and management.

Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant soft-tissue tumor that originates from the skin. It has a slow onset in the early stages, non-specific clinical symptoms, low specificity, and can easily be overlooked, missed, or misdiagnosed by clinicians and pathologists. In addition, DFSP is prone to recurrence after local surgical treatment; however, distant metastasis, especially abdominal metastasis, is rare, which is also a challenge for the accurate diagnosis of DFSP when it progresses distantly. Now a case of abdominal metastasis of DFSP is reported. The patient has been treated with imatinib for ten years, and the lesion has shrunk, but because the patient has been receiving imatinib treatment, his abdominal lesion was once misdiagnosed as gastrointestinal stromal tumor. Therefore, we report on this case to enhance the understanding of the diagnosis and treatment of DFSP, and to provide reference for the pathological diagnosis and precise treatment of such patients. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is an infrequent cutaneous tumour that may involve subcutaneous fat and in some cases fascia, muscles and bone. The infrequent occurrence lessens its clinical awareness in addition to its clinical semblance to many common cutaneous lesions. It is characterized by proclivity for local recurrence. We evaluated the clinical presentation and treatment outcomes of six consecutive cases of DFSP with histologic diagnosis in the University of Calabar Teaching Hospital, Calabar seen between January 2013 and December 2022. This was compared with total cutaneous malignances in the same period. The six consecutive patients comprised of two males and four females (M = F: 1:2) whose ages ranged from 21 to 57 years (mean of 36.5 years) and accounted for 7% of cutaneous malignancies. The site distribution was trunk (back) involved in 3 (50%) of the patients, limbs 3 (50%); upper 1 (17%) and lower limb 2 (33%). Clinical presentation was in the form of firm cutaneous mass with some ulcerated lesions that bled and some fungated. 50 percent of the patients presented with recurrent lesions and in all there was no regional lymphadenopathy or evidence of metastasis. There was a patient with Neurofibromatosis- 1 who had a huge fungated limb lesion offered amputation, four had wide local excision and one incision biopsy. Follow up was poor and the period ranged from 2 to 14 months (mean 7 months). Dermatofibrosarcoma protuberans is an uncommon tumour with clinical semblance to other cutaneous lesions. Early presentation, preoperative histologic diagnosis will enhance the goal of ensuring adequate excision. Adjuvant therapy with Imatinib with or without adjuvant radiotherapy are recommended in the treatment plan in view of the frequency of late presentation with advanced recurrent lesions and poor follow up. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans is a rare low-grade sarcoma, which rarely metastasizes, but it is locally aggressive with a propensity to recur. It usually affects persons of African descent and is extremely rare in childhood with a favourable prognosis. We present a case of paediatric dermatofibrosarcoma protuberans to the midline of the lower back of a 9-year-old Afro-Caribbean boy who was biopsied with a 2-mm margin. After histological confirmation, a 4-cm margin was then performed. Surveillance for recurrence, though none has been seen thus far after 6-month follow-up, will be done for at least 5 years and possibly longer, given this is the first case of this nature ever seen in our institution and the Caribbean region. [ABSTRACT FROM AUTHOR]

Background: Pilomatricoma has various manifestations on color Doppler ultrasound, and a differential diagnosis is challenging. The objective of this study was to investigate which characteristics of skin lesions on color Doppler ultrasound are effective in distinguishing pilomatricoma from epidermoid cyst and dermatofibrosarcoma protuberans. Materials and methods: Records of patients with pilomatricomas (n = 63), epidermoid cysts (n = 76), and dermatofibrosarcoma protuberans (n = 19) who underwent color Doppler ultrasound evaluation and surgical excision were reviewed. The anatomical distribution and color Doppler ultrasound characteristics of these lesions were analyzed. The 63 pilomatricomas were categorized into five types based on their color Doppler ultrasound characteristics, and the roles of these five types in the differential diagnosis of the aforementioned diseases were studied. Results: Pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans exhibited some similar characteristics. Dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity were the major characteristics of pilomatricomas. The pilomatricomas could be categorized into five types, with type II having a diagnostic performance of sensitivity of 65.08%, specificity of 98.95%, area under the receiver operating characteristic curve (AUC) of 0.743, positive predictive value of 97.62%, and negative predictive value of 81.03% for the diagnosis of the aforementioned skin diseases. Conclusion: A combination of dominantly markedly hyperechoic or hyperechoic appearance, posterior acoustic shadowing, and the presence of vascularity exhibits higher diagnostic performance for the differential diagnosis of pilomatricomas, epidermoid cysts, and dermatofibrosarcoma protuberans. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma Protuberans (DFSP) is a rare soft tissue sarcoma distinguished by its infiltrative growth pattern and recurrence potential. Understanding the molecular characteristics of DFSP is essential for enhancing its diagnosis, prognosis, and treatment strategies. The paper provides an overview of DFSP, highlighting the significance of its molecular understanding. The gene expression profiling has uncovered unique molecular signatures in DFSP, highlighting its heterogeneity and potential therapeutic targets. The Platelet-Derived Growth Factor Receptors (PDGFRs) and Fibroblast Growth Factor Receptors (FGFRs) signaling pathways play essential roles in the progression and development of DFSP. The abnormal activation of these pathways presents opportunities for therapeutic interventions. Several emerging therapies, i.e., immunotherapies, immunomodulatory strategies, and immune checkpoint inhibitors, offer promising alternatives to surgical resection. In DFSP management, combination strategies, including rational combination therapies, aim to exploit the synergistic effects and overcome resistance. The article consisting future perspectives and challenges includes the discovery of prognostic and predictive biomarkers to improve risk stratification and treatment selection. Preclinical models, such as Patientderived xenografts (PDX) and genetically engineered mouse models, help study the biology of DFSP and evaluate therapeutic interventions. The manuscript also covers small-molecule inhibitors, clinical trials, immune checkpoint inhibitors for DFSP treatment, combination therapies, rational therapies, and resistance mechanisms, which are unique and not broadly covered in recent pieces of literature. [ABSTRACT FROM AUTHOR]

Simple Summary: Rare diseases represent a major health problem, since patients face difficulties in obtaining a rapid diagnosis and appropriate treatments. Vulvar dermatofibrosarcoma protuberans is one of these rare entities, in which reaching a correct pathological diagnosis is intricate and surgical techniques are not standardised. The aim of our paper is to review the available literature on vulvar dermatofibrosarcoma protuberans to summarise previous experiences and main issues, in an attempt to improve the management of this rare disease. Dermatofibrosarcoma protuberans of the vulva needs to be diagnosed early and managed by a referral centre, where the patient can receive appropriate management: surgical treatment should aim to obtain free margins, lowering the probability of recurrence. Long-term follow up is needed, since recurrences are documented even after several years. Background: Vulvar dermatofibrosarcoma protuberans is an extremely rare disease. Its rarity can hamper the quality of treatment; deeper knowledge is necessary to plan appropriate management. The purpose of this review is to analyse the data reported in the literature to obtain evidence regarding appropriate disease management. Methods: We made a systematic search of the literature, including the terms "dermatofibrosarcoma protuberans", "vulva", and "vulvar", alone or in combination. We selected articles published in English from two electronic databases, PubMed and MEDLINE, and we analysed their reference lists to include other potentially relevant studies. Results: We selected 39 articles, with a total of 68 cases reported; they were retrospective case reports and case series. Dermatofibrosarcoma protuberans of the vulva tends towards local recurrence; an early and timely pathological diagnosis, together with an appropriate surgical approach, are of utmost importance to ensure free margins and maximise the curative potential. Conclusions: Even if this is an indolent disease and it generally shows a good prognosis, appropriate management may help in reducing the rate of local recurrences that may hamper patients' quality of life. Management by a multidisciplinary team is highly recommended. [ABSTRACT FROM AUTHOR]

Introduction: Dermatofibrosarcoma protuberans (DFSP) originated as keloid sarcoma, gaining its current designation in 1925. DFSP exhibits slow growth, categorizing it as a low- to intermediate-grade malignant sarcoma. Initially presenting as a small, firm, irregular skin nodule, it undergoes sudden, rapid growth, forming a prominent mass. While locally aggressive, distant metastasis is rare. DFSP affects mainly the torso then proximal extremities. Case Presentation: In this case study, we described a 57-year-old male individual who presented with a chest midline swelling that was progressing in size. A punch biopsy showed inconclusive results. Thus, a wide local excision was carried out along with sending the initial biopsy slides to Mayo Clinic for second opinion. A diagnosis of DFSP was confirmed, which is an uncommon and locally aggressive tumor affecting soft tissues. The primary histological diagnosis relies on immunohistochemical stains, enabling the distinction between DFSP and other fibrous tumors. Conclusion: Diagnosing DFSP is challenging due to its similarity to other skin lesions. A multidisciplinary approach is vital for accurate diagnosis and management. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) is a rare form of skin cancer characterized by local aggressiveness, typically affecting individuals in the young to middle-aged adult range. The authors of this article aimed to present the clinical picture, as well as the therapeutic approach to a patient undergoing oncological surveillance with DFSP, analyzing the therapeutic response rate based on data published in specialized journals. A 72-year-old man was admitted to the radiation oncology department, having a 75/58 mm tumoral mass on the right posterior cervical region. The patient underwent two radical tumor excision surgeries and interval skin grafting, leading to a negative prognosis for the patient, as the tumor reappeared aggressively in a short period, four months, more exactly. The study highlighted the importance of surgical intervention, such as wide local excision, in preventing recurrence and the major role of initiating timely adjuvant treatment, including radiotherapy. The previously performed studies suggest that radiotherapy can be beneficial following resection with negative margins, and it can serve as primary therapy for patients with inoperable or incompletely excised DFSP. In this case, the only therapeutic response was stopping the progression of the tumor growth and macroscopic changes of the tumor surface with areas of necrosis. This study also discusses the use of imatinib as the only left therapeutic option, due to the lack of radiotherapy response. [ABSTRACT FROM AUTHOR]

Dermatofibrosarcoma protuberans (DFSP) stands as a rare and locally aggressive soft tissue tumor, characterized by intricated molecular alterations. The imperative to unravel the complexities of intratumor heterogeneity underscores effective clinical management. Herein, we harnessed single-cell RNA sequencing (scRNA-seq) to conduct a comprehensive analysis encompassing samples from primary sites, satellite foci, and lymph node metastases. Rigorous preprocessing of raw scRNA-seq data ensued, and employing t-distributed stochastic neighbor embedding (tSNE) analysis, we unveiled seven major cell populations and fifteen distinct subpopulations. Malignant cell subpopulations were delineated using infercnv for copy number variation calculations. Functional and metabolic variations of diverse malignant cell populations across samples were deciphered utilizing GSVA and the scMetabolism R packages. Additionally, the exploration of differentiation trajectories within diverse fibroblast subpopulations was orchestrated through pseudotime trajectory analyses employing CytoTRACE and Monocle2, and further bolstered by GO analyses to elucidate the functional disparities across distinct differentiation states. In parallel, we segmented the cellular components of the immune microenvironment and verified the presence of SPP1+ macrophage, which constituted the major constituent in lymph node metastases. Remarkably, the CellChat facilitated a comprehensive intercellular communication analysis. This study culminates in an all-encompassing single-cell transcriptome atlas, propounding novel insights into the multifaceted nature of intratumor heterogeneity and fundamental molecular mechanisms propelling metastatic DFSP. [ABSTRACT FROM AUTHOR]

Abdulrahman Yousef Alhabeeb,1,2 Ahmed O Idrees,2,3 Thamer S Alhowaish,2,4 Moustafa S Alhamadh,1,2 Emad Masudi,1,2 Abdullah Alanazi,1,2 Wazzan Aljuhani2,3 1College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Ministry of the National Guard-Health Affairs, Riyadh, Kingdom of Saudi Arabia; 2King Abdullah International Medical Research Center, Ministry of the National Guard-Health Affairs, Riyadh, Kingdom of Saudi Arabia; 3Department of Orthopedic Surgery, King Abdulaziz Medical City, Ministry of National Guard - Health Affairs, Riyadh, Saudi Arabia; 4Division of Neurology, King Abdulaziz Medical City, Ministry of the National Guard Health Affairs, Riyadh, Kingdom of Saudi ArabiaCorrespondence: Thamer S Alhowaish, Email thamersa18@gmail.comIntroduction: Dermatofibrosarcoma protuberans (DFSP) is a rare, slow-growing, and locally aggressive soft tissue tumor with a high recurrence rate and metastatic potential, even with the proper treatment.Methods: This was a retrospective (case series) study that took place at King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia, to determine the outcomes of and appropriate margin excision for DFSP. All patients who were diagnosed with DFSP from 2016 to 2021 were included. The following variables were assessed: demographics, tumor characteristics, management options, and most importantly, whether patients were managed with an oncology-oriented approach or a non-oncology-oriented approach.Results: There were a total of seventeen patients with DFSP, four of whom had fibrosarcomatous differentiation (FS-DFSP). The majority (N = 13, 76.5%) of the patients were females. The lower extremities and back were the most common locations for DFSP, accounting for 47.1% and 23.5%, respectively. Only two (11.76%) patients had metastatic disease, one of whom had FS-DFSP. The minimum resection margin was 3 cm, and the maximum was 5 cm. Thirteen (76.47%) patients were managed with an oncology-oriented approach (Group I), 23% of whom had post-excision positive margins. However, all patients who were managed with a non-oncology-oriented approach (Group II) had positive margins post-excision. More than three-quarters (76.9%) of group I underwent wide resection. Split-thickness skin grafting and primary closure were the most commonly used reconstruction methods in groups I and II, respectively. The mean planned margins in groups I and II were 3.9 cm and 1.7 cm, respectively.Conclusion: The findings of this study suggest that a planned wide-margin excision with a minimum safe margin of 3– 5 cm should be implemented to reduce the recurrence, metastasis, and need for further surgeries in patients with DFSP.Keywords: dermatofibrosarcoma protuberans, surgical oncology, management, approach

(1) Background: Rare skin cancers include epithelial, neuroendocrine, and hematopoietic neoplasias as well as cutaneous sarcomas. Ultraviolet (UV) radiation and sunburns are important drivers for the incidence of certain cutaneous sarcomas; however, the pathogenetic role of UV light is less clear in rare skin cancers compared to keratinocyte cancer and melanoma. In this study, we compared the degree of actinic elastosis (AE) as a surrogate for lifetime UV exposure among selected rare skin cancers (atypical fibroxanthoma [AFX], pleomorphic dermal sarcoma [PDS], dermatofibrosarcoma protuberans [DFSP], Kaposi sarcoma [KS], Merkel cell carcinoma [MCC], and leiomyosarcoma [LMS]) while taking into account relevant clinical variables (age, sex, and body site). (2) Methods: We newly established a semi-quantitative score for the degree of AE ranging from 0 = none to 3 = total loss of elastic fibers (basophilic degeneration) and multiplied it by the perilesional vertical extent (depth), measured histometrically (tumor-associated elastosis grade (TEG)). We matched the TEG of n = 210 rare skin cancers from 210 patients with their clinical variables. (3) Results: TEG values were correlated with age and whether tumors arose on UV-exposed body sites. TEG values were significantly higher in AFX and PDS cases compared to all other analyzed rare skin cancer types. As expected, TEG values were low in DFSP and KS, while MCC cases exhibited intermediate TEG values. (4) Conclusions: High cumulative UV exposure is more strongly associated with AFX/PDS and MCC than with other rare skin cancers. These important results expand the available data associated with rare skin cancers while also offering insight into the value of differentiating among these tumor types based on their relationship with sun exposure, potentially informing preventative, diagnostic and/or therapeutic approaches.

Dermatofibrosarcoma protuberans (DFSP) is a superficial low-grade sarcoma, genetically characterized by a fusion gene in collagen type I α (COL1A1) gene and platelet-derived growth factor subunit β (PDGFB). DFSP is locally aggressive and does not typically metastasize. However, DFSP with fibrosarcomatous transformation, which occurs in 7–16% of DFSP cases, demonstrates a poor prognosis than classic DFSP with a higher local recurrence rate and metastatic potential. Although imatinib, a PDGF receptor inhibitor, is a potent therapeutic agent for classic DFSP, it is less effective for DFSP with fibrosarcomatous transformation. The development of definitive chemotherapies for DFSP with fibrosarcomatous transformation is required. Patient-derived tumor cell lines are indispensable tools for preclinical research to discover novel therapeutic agents. However, only seven cell lines were derived from DFSP, out of which only two were established from DFSP with fibrosarcomatous transformation. Hence, in the present study, we established a novel DFSP cell line, NCC-DFSP4-C1, from a surgically resected DFSP tumor specimen with fibrosarcomatous transformation. NCC-DFSP4-C1 harbored an identical COL1A1-PDGFB fusion gene as its donor tumor. NCC-DFSP4-C1 cells retained the morphology of their donor tumor and demonstrated constant proliferation, spheroid formation, and invasion capability in vitro. By screening a drug library, we found that bortezomib and romidepsin demonstrated the strongest suppressive effects on the proliferation of NCC-DFSP4-C1 cells. In conclusion, we report a novel cell line of DFSP with fibrosarcomatous transformation, and demonstrate its utility in the development of novel therapeutic agents for DFSP. [ABSTRACT FROM AUTHOR]