Search

Simple Summary: Desmoplastic melanoma (DM) is a rare subtype of cutaneous melanoma with a distinct clinical presentation, natural history, and response to standard therapies. This review evaluates the role of radiation therapy (RT) in the management of DM, in the context of evolving surgical recommendations and systemic therapy options. Desmoplastic melanoma (DM) is an uncommon subtype of cutaneous melanoma that presents distinct diagnostic and treatment challenges. This review aims to explore the role of adjuvant radiation therapy (RT) in managing DM. To evaluate this question, we reviewed relevant published reports on DM and its treatment and synthesized these findings. It was found that the clinical behavior of DM varies significantly based on its classification as either "pure" DM (pDM, ≥90% desmoplastic features) or mixed DM (mDM, ≤90% desmoplastic features). Patients with pDM have a uniquely high risk of local recurrence but a relatively lower likelihood of nodal disease. Recent studies question the necessity of sentinel lymph node biopsy for pDM patients while illustrating impressive response rates to immune checkpoint inhibition. Most data supporting adjuvant RT predate these changes in surgical management and systemic therapy, yet consistently demonstrate that adjuvant RT reduces the absolute risk of local recurrence by >50%, without significant long-term toxicity. Thus, the existing literature continues to support the conclusion that adjuvant RT effectively reduces the likelihood of local recurrence in pDM patients. Although evolving surgical and systemic therapies are reshaping treatment approaches, adjuvant RT should remain a standard of care. [ABSTRACT FROM AUTHOR]

Simple Summary: Advancements in immune, targeted, and regional therapies have emerged in the past fifteen years in the management of high-risk, advanced, and metastatic melanomas. Rare melanoma variants include acral, mucosal, uveal, and desmoplastic melanoma. Though underrepresented in larger landmark trials for modern therapeutic options, results from these trials have been extrapolated and applied in the management of these rarer subtypes of melanoma. This article aims to review the current treatment recommendations for acral, mucosal, uveal, and desmoplastic melanomas. Rare histologic subtypes of melanoma, including acral, mucosal, uveal, and desmoplastic melanomas, only make up 5% of all diagnosed melanomas and are often underrepresented in large, randomized trials. Recent advancements in systemic therapy have shown marked improvement in pathologic response rates, improving progression-free and overall survival among cutaneous melanoma patients, but there are limited data to demonstrate improved survival among rarer subtypes of melanoma. Acral melanoma has a poor response to immunotherapy and is associated with worse survival. Mucosal melanoma has a large variability in its presentation, a poor prognosis, and a low mutational burden. Uveal melanoma is associated with a high rate of liver metastasis; recent adoption of infusion and perfusion therapies has demonstrated improved survival among these patients. Desmoplastic melanoma, a high-risk cutaneous melanoma, is associated with high locoregional recurrence rates and mutational burden, suggesting this melanoma may have enhanced response to immunotherapy. While these variants of melanoma represent distinct disease entities, this review highlights the clinicopathologic characteristics and treatment recommendations for each of these rare melanomas and highlights the utility of modern therapies for each of them. [ABSTRACT FROM AUTHOR]

Background: Desmoplastic melanoma (DM) is a rare subtype of melanoma characterized by high immunogenicity which makes it particularly suitable for immune checkpoint inhibitors (ICIs) treatment. Case presentation: We report the case of a 53-year-old man with metastatic DM successfully treated with the combination of anti-CTLA-4 and anti-PD-1 antibodies, who developed serious immune-related adverse events (irAEs). The primary tumor was characterized by absent PD-L1 expression and no-brisk lymphocytes infiltration. NGS showed absence of BRAF mutation, a high tumor mutational burden, and an UV-induced DNA damage signature. Metastatic lesions regressed rapidly after few cycles of ICIs until complete response, however the patient developed serious irAEs including hypothyroidism, adrenal deficiency, and acute interstitial nephritis which led to the definitive suspension of treatment. Currently, the patient has normal renal functionality and no disease relapse after 26 months from starting immunotherapy, and after 9 months from its definitive suspension. Conclusion: Efficacy and toxicity are two sides of the same coin of high sensitivity to ICIs in DM. For this reason, these patients should be closely monitored during ICIs therapy to promptly identify serious side effects and to correctly manage them. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma accounts for 5% of all cases of melanoma, but its diagnosis can be difficult due to its frequent clinical presentation with amelanotic lesions. Histologically, spindled melanocytes surrounded by a collagenous stroma are observed. Compared with other types of melanoma, the desmoplastic types presents greater local aggression, and is more prone to local recurrence, but has a lower risk of lymph node metastasis. Early detection, accurate staging, and proper surgical management are the main factors associated with higher survival rates in melanoma patients. Reflectance confocal microscopy (RCM) has proven to be a valuable imaging tool in the diagnosis of skin neoplasms, being useful for orientating practitioners towards the diagnosis of melanoma and indicating the necessity of performing a diagnostic biopsy. We present the case of 52-year-old woman, who presented to the dermatology department with an irregular, dark-colored plaque in the right deltoid region. Dermoscopy showed asymmetry with an atypical network and some areas of regression. RCM revealed pagetoid cells in the upper epidermis, cell atypia, non-edged papillae, dermal inflammation, and nucleated cells in the dermis, which are highly suggestive of melanoma. A biopsy was also performed. A histopathology exam confirmed the diagnosis of superficially spreading melanoma with a desmoplastic component, and revealed a Breslow index of 0.9 mm, Clark level IV, an absence of mitoses, angiolymphatic invasion and regression, and complete excision. The CT and PET-CT scans were negative. A biopsy of the axillary sentinel lymph node was conducted, with a negative result obtained, establishing the IB stage of the disease. The patient will remain under follow-up to look for a recurrence or a new primary melanoma. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma (DM), a type of spindle cell melanoma separated into pure desmoplastic melanoma (PDM) and mixed desmoplastic melanoma (MDM) subtypes, can be a diagnostic challenge and easily confused for dermal scar, especially PDM. We report a 65‐year‐old white man who received a left thumb amputation after an initial biopsy for melanoma, an unclassified type with epithelioid morphology. The amputation and sentinel lymph node specimens were significant for residual melanoma with epithelioid morphology, dermal scar, and a slightly expanded "scar‐like" capsular area in one of seven lymph nodes, which was diffusely positive for SOX10 on reflex sentinel lymph node immunohistochemical protocol. On re‐review of the amputation "scar" like area, a subsequent SOX10 stain confirmed the diagnosis of MDM in this area with epithelioid and spindle cell morphology, significantly upgrading the tumor stage. We share this case to highlight: (i) MDM, although exceptionally uncommon, can result in a pure spindle cell lymph node metastasis, (ii) to encourage increased utilization of SOX10 to assess sentinel lymph node biopsies, especially in the context of melanomas with a spindle cell component, and (iii) share an example of inattentional blindness which was fortunately identified by reflex sentinel lymph node immunohistochemical protocols. [ABSTRACT FROM AUTHOR]

BackgroundDesmoplastic melanoma (DM) is a rare subtype of melanoma characterized by high immunogenicity which makes it particularly suitable for immune checkpoint inhibitors (ICIs) treatment.Case presentationWe report the case of a 53-year-old man with metastatic DM successfully treated with the combination of anti-CTLA-4 and anti-PD-1 antibodies, who developed serious immune-related adverse events (irAEs). The primary tumor was characterized by absent PD-L1 expression and no-brisk lymphocytes infiltration. NGS showed absence of BRAF mutation, a high tumor mutational burden, and an UV-induced DNA damage signature. Metastatic lesions regressed rapidly after few cycles of ICIs until complete response, however the patient developed serious irAEs including hypothyroidism, adrenal deficiency, and acute interstitial nephritis which led to the definitive suspension of treatment. Currently, the patient has normal renal functionality and no disease relapse after 26 months from starting immunotherapy, and after 9 months from its definitive suspension.ConclusionEfficacy and toxicity are two sides of the same coin of high sensitivity to ICIs in DM. For this reason, these patients should be closely monitored during ICIs therapy to promptly identify serious side effects and to correctly manage them.

Desmoplastic melanoma accounts for 5% of all cases of melanoma, but its diagnosis can be difficult due to its frequent clinical presentation with amelanotic lesions. Histologically, spindled melanocytes surrounded by a collagenous stroma are observed. Compared with other types of melanoma, the desmoplastic types presents greater local aggression, and is more prone to local recurrence, but has a lower risk of lymph node metastasis. Early detection, accurate staging, and proper surgical management are the main factors associated with higher survival rates in melanoma patients. Reflectance confocal microscopy (RCM) has proven to be a valuable imaging tool in the diagnosis of skin neoplasms, being useful for orientating practitioners towards the diagnosis of melanoma and indicating the necessity of performing a diagnostic biopsy. We present the case of 52-year-old woman, who presented to the dermatology department with an irregular, dark-colored plaque in the right deltoid region. Dermoscopy showed asymmetry with an atypical network and some areas of regression. RCM revealed pagetoid cells in the upper epidermis, cell atypia, non-edged papillae, dermal inflammation, and nucleated cells in the dermis, which are highly suggestive of melanoma. A biopsy was also performed. A histopathology exam confirmed the diagnosis of superficially spreading melanoma with a desmoplastic component, and revealed a Breslow index of 0.9 mm, Clark level IV, an absence of mitoses, angiolymphatic invasion and regression, and complete excision. The CT and PET-CT scans were negative. A biopsy of the axillary sentinel lymph node was conducted, with a negative result obtained, establishing the IB stage of the disease. The patient will remain under follow-up to look for a recurrence or a new primary melanoma.

ABSTRACTTertiary lymphoid structures (TLS) are ectopic lymphoid structures that can arise in human cancers and are associated with improved overall survival (OS) and response to immune checkpoint blockade (ICB) in several cancers, including non-desmoplastic metastatic melanoma (NDMM). Desmoplastic melanoma (DM) has one of the highest response rates to ICB, and we previously identified that primary DM (PDM) contains TLS. Despite the association of TLS with survival and ICB response, it is unknown whether TLS or associated markers of immune activity can differ between PDM and NDMM. We hypothesized that PDM would contain higher frequencies of TLS than NDMM, that T and B-cell densities and proliferation would be greater in TLS of PDM than TLS of NDMM, and that proliferation rates of T and B-cells in PDM TLS would be concordant with those of intratumoral lymphocytes. We found that four features of TLS in PDM distinguish them from TLS in NDMM. TLS were peritumoral in NDMM but intratumoral in PDM. CD8+ T-cell and CD20+ B-cell densities and proliferative fractions were higher in PDM TLS than NDMM TLS. Additionally, the proliferative fractions of T- and B-cells were concordant between the TLS and tumor site in PDM and discordant in NDMM. Collectively, these data suggest that TLS and associated immune markers can differ across melanoma subsets and suggest that PDM TLS may be more immunologically active and have enhanced immune cell trafficking between tumor and TLS compared to NDMM.

Background: Desmoplastic melanoma is a rare subtype of melanoma mainly appearing on sun-exposed skin. Clinically, it is many times non-pigmented and therefore the diagnosis is often not suspected. Methods: Review article. Results: In this paper we review the main histopathological, immunohistochemical, and molecular features of desmoplastic melanoma, as well as the top 10 morphologic differential diagnoses which should be considered in most cases. The histopathological pattern can be many times deceptive, mimicking a scar, a fibrous reaction, a fibrohistiocytic tumor such as a dermatofibroma, a vascular tumor such as angiosarcoma, a smooth muscle tumor such as leiomyosarcoma, or a neural tumor. Although an overlying atypical junctional melanocytic proliferation may be seen in most cases, it is absent in a significant percentage (up to 30%) of cases, making the diagnosis even more difficult in those instances. The range of diagnostic pitfalls is wide, which may present disastrous prognostic consequences. Conclusion: Desmoplastic melanoma is often a difficult diagnosis to make, as it frequently shows nonspecific clinical findings and overlapping histologic features with many other tumors. However, the potential clinical and prognostic consequences of misdiagnosis as another entity are great. Therefore, this diagnosis must always be kept in mind when encountering spindle cell tumors affecting the head and neck area. [ABSTRACT FROM AUTHOR]

Tertiary lymphoid structures (TLS) are ectopic lymphoid structures that can arise in human cancers and are associated with improved overall survival (OS) and response to immune checkpoint blockade (ICB) in several cancers, including non-desmoplastic metastatic melanoma (NDMM). Desmoplastic melanoma (DM) has one of the highest response rates to ICB, and we previously identified that primary DM (PDM) contains TLS. Despite the association of TLS with survival and ICB response, it is unknown whether TLS or associated markers of immune activity can differ between PDM and NDMM. We hypothesized that PDM would contain higher frequencies of TLS than NDMM, that T and B-cell densities and proliferation would be greater in TLS of PDM than TLS of NDMM, and that proliferation rates of T and B-cells in PDM TLS would be concordant with those of intratumoral lymphocytes. We found that four features of TLS in PDM distinguish them from TLS in NDMM. TLS were peritumoral in NDMM but intratumoral in PDM. CD8+ T-cell and CD20+ B-cell densities and proliferative fractions were higher in PDM TLS than NDMM TLS. Additionally, the proliferative fractions of T- and B-cells were concordant between the TLS and tumor site in PDM and discordant in NDMM. Collectively, these data suggest that TLS and associated immune markers can differ across melanoma subsets and suggest that PDM TLS may be more immunologically active and have enhanced immune cell trafficking between tumor and TLS compared to NDMM. [ABSTRACT FROM AUTHOR]

Resumen: El melanoma desmoplásico (MD) representa entre el 0,4-4% de todos los melanomas. Se presenta como un tumor constituido predominantemente por melanocitos fusiformes amelanóticos inmersos en un estroma colágeno abundante. Se clasifica en MD puro o mixto, basándose en la proporción de melanoma desmoplásico frente a la del melanoma no desmoplásico presente en el tumor infiltrante. En el MD puro el componente desmoplásico representa más del 90% del melanoma infiltrante mientras que, en el MD combinado o mixto, el componente desmoplásico representa menos del 90%.El MD es más frecuente en varones (ratio 1,7-2:1); la edad media al diagnóstico oscila entre 66-69 años y suele localizarse en áreas de fotoexposición crónica, a menudo asociado a un lentigo maligno. Su reconocimiento clínico es difícil ya que se presenta como una pápula o placa no pigmentada, indurada y de bordes mal definidos, que recuerda a una cicatriz.El MD es un tumor con una alta tendencia a la recurrencia local y en el caso del MD puro, una baja tendencia a la diseminación ganglionar. Sin embargo, en las series más contemporáneas, su pronóstico global parece ser similar al de melanomas no desmoplásicos (MND) del mismo grosor. Su abordaje clínico posee algunos matices diferenciales, en comparación al resto de melanomas, que se revisan en el presente trabajo. Abstract: Desmoplastic melanoma (DM) accounts for 0.4% to 4% of all melanomas. These skin tumors are mainly formed by amelanotic spindled melanocytes immersed in an abundant collagen stroma and are classified as pure when the desmoplastic component accounts for at least 90% of the invasive tumor and as mixed or combined otherwise. DMs are more common in men (male to female ratio, 1.7 to 2:1), and the mean age at diagnosis is 66 to 69 years. The tumors tend to occur in chronically sun-exposed areas, often in association with lentigo maligna, and are difficult to recognize because they can resemble a scar, presenting as a firm, unpigmented papule or plaque with poorly defined borders. DMs also have a strong tendency to recur locally, and pure variants rarely spread to the lymph nodes. Nonetheless, recently published series suggest that patients with DM have a similar prognosis to those with nondesmoplastic melanoma of the same thickness. The clinical management of DM varies in certain aspects from that of other melanomas and is reviewed in this article.

Distinguishing desmoplastic melanomas (DMs) from neurofibromas (NFs) can be histologically challenging in some cases. To date, a reliable marker to differentiate the 2 entities has remained elusive. S100 subtyping and CD34 fingerprinting have been proposed, but controversy remains as to their reliability. Missense mutations in TP53 are often found in DMs, resulting in a dominant negative effect and paradoxical accumulation of the tumor suppressor protein p53. We hypothesized that p53 may be expressed differentially in DMs, making it a valuable tool in differentiating DMs from NFs. Using immunohistochemistry, we compared p53 protein expression in 20 DMs and 20 NFs retrieved from our tissue archives and stained with p53 antibody (Monoclonal, DO-7). Patients with DM included 18 men and 2 women (age, 36 to 95 y; mean, 70.5 y; median, 70 y). Fifteen (15/20) tumors occurred in head and neck area; 2 (2/20) on the trunk; and 3 (3/20) on the extremities. Patients with NF included 12 men and 8 women (age, 47 to 85 y; mean, 65.2 y; median, 69.5 y). Eleven (11/20) tumors occurred on the trunk, 6 (6/20) on the extremities, and 3 (3/20) on the head and neck area. A total of 19/20 (95%) DMs were positive for p53. DM Histo-scores ranged from 0 to 300 (mean, 203; median, 260). Nuclear accumulation of p53 was seen in all 19 positive DMs. None of the 20 NFs were positive for p53 (2-tailed t test P-value

Desmoplastic melanoma (DM) is a less common form of cutaneous melanoma that has been described for decades; however, controversy remains regarding the management and use of sentinel lymph node biopsy (SLNB). The purpose of this study is to identify whether SLNB is indicated in all cases of DM, including the pure subtype. A systematic review was conducted using PubMed (with access to MEDLINE) along with the Cochrane Central Register of Controlled Trials from 2001 to 2019. Case series and case-control studies were included. Eighteen studies were included for a total population of 3,914 patients. SLNB was performed in 2229 patients. The percentage of positive SLNB results was 8.5%. However, patients with pure DM (>90% desmoplastic component) were found to have a significantly lower rate of occult metastatic node positivity when compared with that of mixed DM (4.9% and 14.8%, respectively). Our findings underscore the importance of the pathologist reporting percentage of desmoplastic component in melanoma. SLNB should be strongly considered for patients with mixed DM. However, the low rate of occult metastatic node positivity in pure DM is beneath the threshold for using SLNB as a staging procedure. Previous studies have suggested that desmoplastic melanoma is less likely to metastasize to regional lymph nodes when compared with conventional melanoma. This review suggests that it is imperative to distinguish the histologic subtype of desmoplastic melanoma to determine if staging procedure is indicated. [ABSTRACT FROM AUTHOR]

Superficial malignant peripheral nerve sheath tumors (SF-MPNSTs) are rare cancers and can be difficult to distinguish from spindle cell (SCM) or desmoplastic (DM) melanomas. Their biology is poorly understood. We performed whole-exome sequencing (WES) and RNA sequencing (RNA-seq) on SF-MPNST (n=8) and compared these to cases of SCM (n=7), DM (n=8), and deep MPNST (D-MPNST, n=8). Immunohistochemical staining for H3K27me3 and PRAME was also performed. SF-MPNST demonstrated intermediate features between D-MPNST and melanoma. Patients were younger than those with melanoma, and older than those with D-MPNST; outcome was worse and better respectively. SF-MPNST tumor mutational burden (TMB) was higher than D-MPNST and lower than melanoma; differences were significant only between SF-MPNST and SCM (p = 0.0454) and between D-MPNST and SCM (p = 0.001, Dunn's Kruskal-Wallis post-hoc test). Despite having an overlapping mutational profile in some common cancer-associated genes, the COSMIC mutational signatures clustered DM and SCM together with ultraviolet light exposure signatures (SBS7a, 7b), and SF- and D-MPNST together with defective DNA base excision repair (SBS30, 36). RNA-seq revealed differentially expressed genes between SF-MPNST and SCM (1670 genes), DM (831 genes), and D-MPNST (614 genes), some of which hold promise for development as immunohistochemical markers (SOX8, PLCH1) or aids (MLPH, CALB2, SOX11, TBX4). H3K27me3 immunoreactivity was diffusely lost in most D-MPNSTs (7/8, 88%), but showed variable and patchy loss in SF-MPNSTs (2/8, 25%). PRAME was entirely negative in the majority (0+ in 20/31, 65%), including 11/15 melanomas, and showed no significant difference between groups (p=0.105, Kruskal-Wallis test). Expression of immune cell transcripts was upregulated in melanomas relative to MPNSTs. Next-generation sequencing revealed multiple differential features between SF- MPNST, D-MPNST, SCM, and DM, including tumor mutation burden, mutational signatures, and differentially expressed genes. These findings help advance our understanding of disease pathogenesis and improve diagnostic modalities., (Copyright © 2024. Published by Elsevier Inc.)

Numerous cells with very large and irregular nuclei ("monster" cells) have not hitherto been reported in desmoplastic melanoma (DM). Their prognostic significance in melanomas is a matter of debate, although some authors have associated them with more aggressive tumor behavior. We report a mixed DM on the scalp of an 88-year-old woman imitating an atypical fibroxanthoma. Tumor cells stained positive for SOX10, S100, and cyclin D1; BRAF mutation status was negative, and fluorescence in situ hybridization analysis showed copy number gains in 11q13 (cyclin D1) and 6p25 (RREB1), and loss in 6q23 (MYB). Cyclin D1 amplification is associated with poor prognosis in melanoma. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma is a rare variant of melanoma and it does not show the classical clinicopathological features of melanoma. Immunohistochemically HMB-45 and Melan-A negativity in desmoplastic melanoma creates difficulty in diagnosis and causes misdiagnosis. For this reason, additional immunohistochemical markers besides S-100 are needed. In our case series, we aimed to investigate the diagnostic utility of fascin as an ancillary marker for the diagnosis of desmoplastic malignant melanoma. Sections obtained from five desmoplastic malignant melanoma cases diagnosed histopathologically and immunohistochemically were stained by automated slide stainer for immunohistochemistry. The cases showing cytoplasmic immunoreactivity were evaluated as 'positive' and the ones with no immunoreactivity as 'negative'. All desmoplastic melanoma cases with immunohistochemically negative for melanocyte markers except S-100 were positive for fascin. Fascin positivity was diffuse and strong in three cases. There is a difficulty in diagnosis of desmoplastic melanoma due to its peculiar clinical and histopathological features. Accurate differential diagnosis is extremely important for the correct treatment of the demoplastic melanoma. Therefore, we think that showing fascin positivity besides S-100 will be also useful in the diagnostic process. [ABSTRACT FROM AUTHOR]

Background: Perineuriomatous nevi are rare and diagnostically problematic. We report a series of eight perineuriomatous nevi to highlight the diagnostic features. Methods: Cases were retrospectively reviewed and characterized. Results: Median age was 42.5 years (range 25‐64), with equal sex distribution. Lesions occurred on the arm (n = 4), trunk (n = 2), and head/neck (n = 2). Median size was 7.5 mm (range 5‐12 mm). Clinical differential diagnoses included atypical nevus (3), blue nevus (1), neurofibroma (1), and dermatofibroma (1). Lesions were circumscribed, dome‐shaped (5/8), and biphasic (8/8) with nested epithelioid cells and wavy spindled cells arranged in whorled fascicles in a myxocollagenous stroma. When present, junctional growth was lentiginous (4/8). No cases displayed pleomorphism or mitotic figures. The perineuriomatous component stained positively for epithelial membrane antigen (8/8 focal to diffuse) and CD34 (4/5 focal to diffuse). SOX10 and S100 protein stained all nevoid cells and in some cases a subset of intermingled spindled cells in perineuriomatous areas, where other melanocytic markers were negative. p16 protein expression was uniformly retained (3/3), and p53 negative (0/2). Nevoid cells in most lesions were positive for BRAFV600E (5/7). Ki67 was mildly elevated (~5%) in 3/3 cases. Conclusions: Recognizing the histopathologic and immunophenotypic features in these unusual nevi helps avoid overdiagnosis. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma (DM) is a rare variant of melanoma with distinct clinical, histopathologic, and immunohistochemical features. Clinically, DM differs from conventional melanoma by a higher propensity for local recurrence and less frequent metastatic spread to regional lymph nodes. In its pure form, DM has a distinct appearance displaying a low density of fusiform melanocytes in a collagen-rich matrix. Whereas a number of mutations have been identified in primary melanoma, including BRAF, NRAS, GNAQ, GNA11, and KIT, and the occurrence of these mutations has been found to correlate to some extent with the histopathologic features, anatomic site, and/or mode of sun exposure, no distinct set of mutations has so far been reported for DM. To study the potential association of neurofibromin (NF1) mutations with DM, we examined 15 desmoplastic and 20 non-DMs by next-generation sequencing. Mutations of the NF1 gene were found in 14 of 15 (93%) DMs and 4 of 20 (20%) non-DMs. The high frequency of NF1 mutations in DMs suggests an important role for NF1 in the biology of this type of melanoma.

Desmoplastic melanoma (DM) is a rare form of malignant melanoma. DMs may present with a non-specific appearance which can make diagnosis difficult. Surgical excision with wide margins is the preferred treatment. DMs tend to be locally aggressive and adjuvant radiotherapy may improve local control of disease.

Desmoplastic melanoma (DM) is a variant of melanoma, which typically affects chronically sun-damaged skin of elderly patients. Pure DM displays a low density of fusiform melanocytes in a collagen-rich matrix. In mixed DM, tumor cell density is higher, and parts of the tumor lack abundant stromal fibrosis. Both pure and mixed DMs usually express S100 protein homogenously. We report herein an unusual biphenotypic tumor characterized by the association of a pure DM with an undifferentiated solid spindle cell nodule. It occurred on the scalp of a 66-year-old man. A biopsy of the undifferentiated spindle cell nodule was initially interpreted at a commercial laboratory as atypical fibroxanthoma. The pure DM was seen only in the excisional specimen. All cells of the pure DM stained for S100 protein and SOX10. The adjacent solid sarcomatoid spindle cell nodule lacked expression of S100 protein, SOX10, as well as melan-A, gp100, and microphthalmia-associated transcription factor in >95% of its tumor cells. Although focal expression of melanocyte differentiation antigens in the solid tumor component made us favor a combined DM with sarcomatoid dedifferentiation, we also considered the possibility of a collision scenario, that is, a pleomorphic dermal sarcoma incidentally colliding with a DM. To further assess a possible relationship of the sarcomatoid nodule with the DM, we performed next-generation sequencing analysis on each component separately. The analysis revealed shared chromosomal copy number changes and a high number of common mutations, thereby supporting the concept of a DM with a dedifferentiated sarcomatoid component. An interesting finding is the presence of mutations of the neurofibromin 1 (NF1) gene in both tumor components.

: The term neurotropic melanoma has been used to refer to malignant melanoma with associated infiltration of nerve or "neural differentiation"--that is, melanoma cells exhibiting cytological characteristics of nerve cells. Historically, neurotropic melanoma has generally been discussed within the context of desmoplastic melanoma. We report an exceptional case of melanoma notable for a very well-differentiated neural component that was contiguous with obvious overlying melanoma. After careful consideration of all pertinent histological features, the overall diagnostic impression was that of melanoma with associated "malignant neurotization." We have not encountered a previously reported case with such a well-differentiated neural component. The following article details our exceptional case of melanoma with "malignant neurotization" and presents a discussion of the differential diagnosis and brief review of the pertinent literature.

Desmoplastic malignant melanoma is a rare variant of spindle cell melanoma commonly seen in older adults on sun-exposed areas. It accounts for 1–4 % of all cases of cutaneous melanoma. The common location of the desmoplastic melanoma is the head and neck region, whereasother sites are less common. A 45-year-old male presented with an proliferative growth on nose, after a trauma that was diagnosed as tumor. Histopathological examination with the help of wide panel of immunohistochemical methods and with emphasis on SOX10, was, after a broad diferential diagnosis concluded as a desmoplastic melanoma.

Purpose: To investigate the clinicopathological characteristics and immunophenotype of desmoplastic melanoma (DM) in the Chinese population. Patients and Methods: We report three cases of DM diagnosed by the Pathology Department of Shanghai Dermatology Hospital. We describe the clinical and pathological characteristics of the three cases and examine molecular markers used in the diagnosis of DM. Finally, we summarize the current literature in the DM field. Results: Clinically, lesions in the three DM patients were characterized by non-pigmented nodules or papules. Microscopically, we observed an abundance of fibrous interstitium mixed with spindle cells exhibiting various degrees of atypia. Occasionally, these structures exhibited changes in lentigo maligna at the epidermal junction, accompanied by the presence of lymphoid follicular structures and neurophilic behavior. Diagnosis of DM was confirmed by immunohistochemical staining, which revealed high expression levels of S-100 and SOX-10. Melanocyte markers were focally positive or negative. Unlike DMs from other populations, our three patients were negative for WT-1 and P53. All three cases received surgical resection, which is the preferred treatment for DM, and none of the patients experienced recurrence. Conclusion: DM in these Chinese patients was similar to that observed in other DM populations in terms of immunophenotype and clinical and histological features. A notable absence in p53 staining was observed in the three cases reported here, suggesting that p53 negativity should not exclude the diagnosis of DM in the Chinese population. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma commonly occurs on the head and neck in a pure form, but occasionally, it occurs in a mixed tumor with another type, usually superficial spreading melanoma (SSM), and rarely as a metastasis from a primary SSM. We report here a primary SSM on the leg of a 32-year-old male which metastasised to lymph nodes, and 10 years later recurred at the primary site initially with mixed features but evolving to resemble a uniformly desmoplastic, deeply invasive melanoma. This unusual case has implications for clinical management and is additionally notable for its reversal in behavior, from metastatic to local infiltrative type, correlating with the change in morphology. [ABSTRACT FROM AUTHOR]

The development of flat pigmented lesions on chronically sun‐damaged (CSD) skin of the face may represent the clinical manifestation of a wide variety of hyperplastic/neoplastic melanocytic proliferations. We report the exceptional case of an acquired pigmented patch occurring on CSD skin, histopathologically characterized by diffuse hyperplasia of dendritic/spindled melanocytes in the superficial dermis within a widened band of actinic elastosis. This lesion was associated with a small focus of early invasive lentigo maligna melanoma (LMM). We show the melanocytic nature of the population of dermal pigmented cells by means of single and double immunohistochemical staining for melanocytic and histiocytic markers. The biologic significance of the focus of LMM within the hyperpigmented lesion (whether random collision phenomenon or causally related occurrence), as well as the pathogenesis of the whole dermal lesion are difficult to elucidate. Our case emphasizes the need for a better understanding of the pathophysiology of so‐called dermal melanocytes. [ABSTRACT FROM AUTHOR]

Copyright of Medicina (Buenos Aires) is the property of Medicina (Buenos Aires) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are multiple, genetically distinct pathways that give rise to melanoma. Melanomas on sun-damaged skin (MSDS), including lentigo maligna and desmoplastic melanoma, have distinct genetic profiles and are uniquely linked to chronic ultraviolet exposure. In this article, we discuss the etiologies of lentigo maligna and desmoplastic melanoma, emerging diagnostic adjuncts that might be helpful for accurately identifying these lesions, and the clinical relevance of their frequent co-occurrence. We present unique and overlapping features of these entities and discuss challenges in MSDS management, including margin assessment, excision, and the potential role of nonsurgical therapy. Last, we address the role of immunotherapy in invasive disease. Understanding MSDS as distinct from melanoma arising on intermittently sun-exposed or sun-protected skin will ultimately help optimize patient outcomes. [ABSTRACT FROM AUTHOR]

Background: Positive staining for SOX10 and the S100 protein are often used in the evaluation of challenging melanocytic neoplasms including melanoma in patient samples. SOX-10 positivity of non-melanocytes in re-excision specimen could complicate the evaluation of invasive melanoma with an invasive desmoplastic component. Therefore, quantifiable data regarding the positivity of SOX-10 in scars will help dermatopathologists to better identify false positive staining. Methods: A retrospective analysis was performed on 50 re-excision specimens from 2013 to 2017, with a diagnosis of squamous cell carcinoma (SCC) or squamous cell carcinoma in situ (SCCIS). Blocks of re-excision specimens containing scars were stained for SOX-10; results were evaluated by a board-certified dermatopathologist. The sum of the five highest numbers of high-power field (HPF) counts as a proxy for “SOX-10 stain factor," and cell morphological features were analyzed. MART-1 and CD68 immunohistochemical staining was performed to study possible lineage of these SOX-10 positive cells. Results: All 50 specimens showed varying degrees of SOX-10 positivity for histiocytes. SOX-10 positive histiocytes were present in 86% of re-excision scar tissues, of which 71.3% had spindle-shaped or angulated nuclei, and 61.8% had nuclear sizes larger than typical lymphocytes (7 μm). Within the same area of scars, CD68 staining was floridly positive, where as MART-1 staining was overwhelmingly negative. Conclusions: This study illustrates a potential diagnostic pitfall of using SOX-10 to evaluate re-excision specimens of melanocytic neoplasms and also suggests a previously undescribed staining pattern in scars of SOX-10 positive cells that are not melanocytes. We postulate that such SOX-10 positive cells may represent a small fraction of histiocytes routinely found in scar tissue. [ABSTRACT FROM AUTHOR]

Desmoplastic melanoma (DM) is a rare morphological subtype of melanoma that remains uncharacterized. The aim of the present study was to investigate the incidence of DM, its general demographics, clinicopathological features and disease-specific prognostic factors. DM cases were sampled from the Surveillance, Epidemiology and End Results (SEER) program from between 1973 and 2017. A total of 3,657 cases (median age, 68 years) were identified. The results indicated that DM primarily occurred in Caucasian subjects, with a male-to-female ratio of 2:1. Statistically significant overall survival (OS) and disease-specific survival (DSS) rate differences were identified according to sex, age, treatment, T stage, N stage and SEER historic tumor stage (P<0.05). In multivariate Cox regression analysis, age >68 years, male sex, American Joint Committee on Cancer (AJCC) stage II and III, and SEER historic tumor stage of the regional tumor were all factors associated with poorer OS and DSS rates. The findings also revealed that surgical treatment was associated with favorable DSS and OS rates. In conclusion, DM occurred primarily in Caucasian subjects of 60–80 years of age, with predominance in males. Furthermore, age, sex, AJCC stage, SEER historic tumor stage and surgical treatment were identified as independent prognostic factors of DM in terms of DSS and OS. [ABSTRACT FROM AUTHOR]