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Dermatofibroma, also known as “fibrous histiocytoma”, is one of the most common cutaneous soft-tissue tumors. Many variants of dermatofibromas have been described, and knowledge of these variations is important to avoid misdiagnosis of a possibly more aggressive tumor. Histological features of different variants can coexist in the same lesion, but typical common fibrous histiocytoma features are generally found, at least focally, in all cases. However, when cellular changes make up the majority of the lesion, the histopathological diagnosis can become more complex and requires immunohistochemical investigations for correct nosographic classification. We present the case of a cutaneous fibrous histiocytoma, “granular cell” variant, found on the left leg of a 74-year-old woman.

The ossifying variant and the granular cell variant are rare subtypes of cutaneous fibrous histiocytoma (CFH), characterized by islands of mature metaplastic bone tissue rimmed by multinucleated osteoclast-like giant cells and by large-sized cells with granular cytoplasm and mildly hyperchromatic nuclei with inconspicuous nucleoli, respectively. We herein present two cases of these unusual CFH variants in a 37-year-old woman and in a 38-year-old man, respectively. The main differential diagnoses, including both benign and malignant lesions, are also discussed.

Aneurysmal fibrous histiocytoma (AFH) is a rare variant of benign fibrous histiocytoma. This tumor accounts for less than 2% of all fibrous histiocytomas, 1.7% of all cutaneous fibrous histiocytoma and it is typically known to occur in the extremities of middle-aged patients. A 23 year old male presented with slow growing, pigmented, nodular lesion on the left leg for the past 2 years. The swelling was initially non-tender, but there was a sudden increase in size associated with pain for the past 2 months. With a clinical suspicion of malignant melanoma an excision biopsy was performed and further evaluated by histopathology. The skin covered pigment lesion measuring 1.5x0.8x0.5cm showed fibrohistiocytic cellular proliferations containing blood filled spaces lacking endothelium on microscopy. Ancillary testing with bleaching, perls prussion blue reaction demonstrated the pigment as hemosiderin. Subsequently the lesion was negative for CD34 and positive for Factor XIIIA. Based on the histomorphology, ancillary testing and IHC, the diagnosis of Aneurysmal fibrous histiocytoma was made. Aneurysmal fibrous histiocytoma can be a challenging diagnostic entity due to its close clinical resemblance to melanoma and hemngioma. Although the pathogenesis is unclear, it is believed to be caused by extravasation of erythrocytes from capillaries leading to formation of the cystic blood spaces.

Deep benign fibrous histiocytoma (DBFH) is a rare mesenchymal tumor compared with cutaneous fibrous histiocytoma. As the diagnosis of DBFH may be clinically difficult, the presence of DBFH is usually confirmed after its excision. In this case study, we report a case of a 31-year-old man who lived with a painless mass in his right thigh for 15 years. After its examination by preoperative ultrasound and magnetic resonance imaging, the tumor was completely excised. Further histologic evaluation revealed neoplastic growth composed of proliferating spindle cells forming short fascicles and a storiform pattern. The patient was diagnosed with DBFH on the basis of its intraoperative, radiologic, and histopathologic features. Keywords: Benign fibrous histiocytoma, Soft tissue tumor, DBFH subcutaneous, Thigh

Cutaneous fibrous histiocytoma (cFH) is a common benign mesenchymal neoplasm. Although most cases of cFH behave indolently, rare cases have been reported that show aggressive behavior. At least 41 cases of metastatic fibrous histiocytoma (metFH) have been previously reported, with only eleven cases of fibrous histiocytomas that eventually metastasized analyzed with aCGH thus far. These limited studies have proposed that the number of chromosomal aberrations increases along a spectrum in cutaneous fibrous histiocytomas, making array-based comparative genomic hybridization (aCGH) a potential tool for recognizing aggressive cFHs and metastatic disease, especially when the time interval from the primary diagnosis is prolonged. Herein, we report a case of metastasizing cellular fibrous histiocytoma in which aCGH analysis of the primary and metastatic tumors demonstrated multiple shared chromosomal aberrations, helping support metastatic disease (nine years out from the initial diagnosis) and briefly review the current literature on aCGH and its role in predicting aggressive behavior in such neoplasms. Keywords: Cutaneous fibrous histiocytoma, Array-based comparative genomic hybridization, Cellular fibrous histiocytoma, Metastasizing fibrous histiocytoma

Aneurysmal fibrous histiocytoma is often clinically misdiagnosed. In this study, we put forward an insight on how to help diagnose this disease clinically. A retrospective chart review was performed on all patients diagnosed with aneurysmal fibrous histiocytoma from 2007 to 2017 in the Department of Dermatology, Union Hospital, China, and all clinical data were collected from the hospital archives. From a total of 418 patients diagnosed with cutaneous fibrous histiocytoma, only 30 patients were confirmed to have aneurysmal fibrous histiocytoma out of which only 2 patients were clinically diagnosed with aneurysmal fibrous histiocytoma. The remaining 28 patients were diagnosed with various types of vascular tumors although pathology classified them as having aneurysmal fibrous histiocytoma. Among the 30 patients, 9 were male and 21 were female. There were following age groups: 13-19 (mean 16, n=4), 20-29 (mean 26.25, n=8), 30-39 (mean 33, n=7), 40-49 (mean 44, n=4), 50-59 (mean 56.75, n=4), 60 and above (mean 61, n=3). Tumors were present on the head, neck, back, waist, hips and upper and lower extremities. After complete excision, there was no recurrence and no complications. Histologically, lesions showed the typical pseudoangiomatoid spaces without endothelial lining and infiltration of fibrohistiocytes in hemosiderotic pigmentation. It was suggested that although the prognosis of aneurysmal fibrous histiocytoma is good, accurate diagnosis is paramount to avoid clinical misdiagnosis and subsequent complications.

Objectives: While useful in diagnosing angiosarcomas, CD31 can also highlight histiocytes within soft tissue tumors and lead to errors in diagnosis. We sought to determine how often CD31 highlights cutaneous histiocytomas and histiocytoma mimics. Methods: We examined eight epithelioid cell histiocytomas (ECHs), 12 xanthogranulomas (XGs), nine cases of Langerhans cell histiocytosis (LCH), eight reticulohistiocytomas, 11 xanthomas, 29 atypical fibroxanthomas, nine granular cell tumors, four cases of angiolymphoid hyperplasia with eosinophilia, nine intradermal Spitz nevi, and nine angiosarcomas with antibodies directed against CD31, CD34, CD163, and factor VIII. Results: CD31 marked cells in three of 12 XGs, four of nine cases of LCH, one of eight reticulohistiocytomas, one of 11 xanthomas, 10 of 29 atypical fibroxanthomas, four of four cases of angiolymphoid hyperplasia with eosinophilia, nine of nine angiosarcomas, zero of nine granular cell tumors, and zero of eight ECHs. CD34 and factor VIII were negative in all nonvascular cases. Conclusions: Our results indicate that CD31 can mark lesional cells and imitate vascular tumors in cutaneous histiocytomas and histiocytoma mimics, an error that can be avoided by using a panel of antibodies.

Epithelioid fibrous histiocytoma is a rare and distinctive cutaneous neoplasm. Most cases harbor ALK rearrangement and show ALK overexpression, which distinguish this neoplasm from conventional cutaneous fibrous histiocytoma and variants. SQSTM1 and VCL have previously been shown to partner with ALK in one case each of epithelioid fibrous histiocytoma. The purpose of this study was to examine a large cohort of epithelioid fibrous histiocytomas by next-generation sequencing to characterize the nature and prevalence of ALK fusion partners. A retrospective archival review was performed to identify cases of epithelioid fibrous histiocytoma (2012-2016). Immunohistochemistry was performed to confirm ALK expression. Targeted next-generation sequencing was applied on RNA extracted from formalin-fixed paraffin-embedded tissue to identify the fusion partners. Twenty-three cases fulfilled inclusion criteria. The mean patient age was 39 years (range, 8-74), there was no sex predilection, and >75% of cases involved the lower extremities. The most common gene fusions were SQSTM1-ALK (N=12; 52%) and VCL-ALK (N=7; 30%); the other four cases harbored novel fusion partners (DCTN1, ETV6, PPFIBP1, and SPECC1L). The pattern of ALK immunoreactivity was usually granular cytoplasmic (N=12; 52%) or granular cytoplasmic and nuclear (N=10; 43%); the case containing an ETV6 fusion partner showed nuclear staining alone. There was no apparent relationship between tumor morphology and the ALK fusion partner. In summary, SQSTM1 and VCL are the most common ALK fusion partners in epithelioid fibrous histiocytoma; DCTN1, ETV6, PPFIBP1, and SPECC1L represent rare fusion partners. The proteins encoded by these genes play diverse roles in scaffolding, cell adhesion, signaling, and transcription (among others) without clear commonalities. These findings expand the oncogenic promiscuity of many of these ALK fusion genes, which drive neoplasia in tumors of diverse lineages with widely varied clinical behavior. This is the first documented account of ETV6-ALK and SPECC1L-ALK translocations in neoplasms.

Aneurysmal Fibrous Histiocytoma (AFH) is a distinct and a rare clinicopathological variant of Cutaneous Fibrous Histiocytoma (CFH). It differs from the usual benign fibrous histiocytoma clinically and morphologically with high rate of recurrence. Here, we report a case of AFH with history of recurrence which presented as a polypoid swelling and showed vascular spaces with no endothelial lining which was proved negative by CD34 immunostaining. The spaces were bordered by tumour cells.

Background: Cutaneous fibrous histiocytoma (CFH) is a common, benign skin tumor predominantly occurring on the extremities or trunk. However, CFH on the finger is rare. Objective: This study was undertaken to examine the clinicohistopathological features of CFH of the finger. Materials and Methods: This is a retrospective study of 12 CFHs located on fingers in a tertiary hospital in Korea. All case slides were retrieved from saved files. Results: Ages of the CHF of the finger affected individuals ranged from 9 to 48 years with a male-to-female ratio of 1.4:1. Picker's nodule or wart was the most common clinical diagnosis. In only 2 out of the 12 cases was the pre-biopsy diagnosis of CFH ventured. Fibrocollagenous type was the most common histological type. Majority of the cases were mitotically inactive, exhibiting only 0–1 mitoses per high-power field and there was no recurrence. Tumor cells were uniformly CD34 negative. Conclusion: Because CFH can resemble malignancies including dermatofibrosarcoma protuberans, a lack of familiarity with the occurrence of CFH of the finger may lead to more aggressive treatment. Dermatologists should include CFH in their differential diagnosis of circumscribed nodules on the fingers to ensure proper management.

Background Cutaneous fibrous histiocytoma (FH) is a common mesenchymal neoplasm. Metastasis is rare, disproportionately occurring among the aneurysmal, cellular, atypical, and deep variants. Objective We determined whether DNA copy number changes occurred in atypical FH (AFH), and whether they were similar to those in metastasizing FH (MetFH) and benign cellular FH (CFH). Methods Five primary tumors of MetFH were evaluated by array-based comparative genomic hybridization analysis, with tissue from local recurrences and lung metastases in 2 and 2 patients, respectively. Seven indolent AFH and 5 CFH were identified for comparison. Results Substantial differences between the groups were found both in the frequency of chromosomal aberrations (higher among MetFH and absent or solitary in CFH) and array-based comparative genomic hybridization profiles (frequent gains of 7 and 8q and losses of Xq in MetFH; recurrent losses of chromosomes 9 and 22 in AFH; isolated loss of 5q and gain in chromosome 20 in 2 CFH). Fatal MetFH cases (2 of 5 cases) exhibited the highest rate of chromosomal aberrations. Limitations This study included a small sample size with a short-term follow-up. Conclusions Benign CFH, indolent AFH, and MetFH represent distinct biological entities within the spectrum of FH; array-based comparative genomic hybridization may be a tool in recognizing FH cases with metastatic potential and increasingly aggressive behavior.

Background: Cellular benign fibrous histiocytoma (CBFH) represents a morphologic variant of cutaneous fibrous histiocytoma (FH). Because of its relative monomorphism and frequent fascicularity, CBFH can easily be mistaken for a malignancy. In fact, CD34, often used to distinguish CBFH from dermatofibrosarcoma protuberans (DFSP), can also be positive. To add to the confusion, desmin positivity may also be observed in a subset of CBFH. Desmin and CD34 expression often cause interpretative difficulty which may lead to misdiagnosis. Our aim was to examine the incidence of desmin and CD34 expression in CBFH. Methods: One hundred consecutive cases of morphologically typical CBFH were retrieved from consultation files. Clinicopathologic and immunohistochemical features were evaluated. Results: SMA positivity was found in tumor cells in 93 of 100 cases (93%). Desmin positivity was found in 32 of 100 cases (32%). CD34 was positive in 6 of 100 cases (6%). There was no evident correlation between immunophenotype and anatomic site or other clinical variables. Conclusion: Frequent desmin (32%) and occasional CD34 (6%) expression are encountered in CBFH. Desmin positivity can be explained on the basis of myofibroblastic differentiation. The occasional CD34 positivity in a subset of CBFH should not be a deterrent from making the correct pathologic diagnosis, based on characteristic morphologic features.

Atypical fibrous histiocytoma is a rare and a distinct variant of cutaneous fibrous histiocytoma which can be misdiagnosed as sarcoma. It is mainly composed of a mixture of fibroblastic and histiocytic cells, especially found in the skin (dermatofibroma), particularly in the limbs. It is quite uncommon and is difficult to distinguish from a malignant lesion. Due to the lack of clear cut predictive morphological patterns and due to the suspicion of malignancy, complete surgical excision is recommended. Provided that atypical fibrous histiocytoma is treated by complete excision, a benign outcome is to be expected in most cases. However, like the cellular and aneurysmal variants of fibrous histiocytoma, atypical fibrous histiocytoma shows a higher tendency to recur locally than ordinary fibrous histiocytoma and may rarely metastasize. Lesions with floridly atypical features represent potential pitfalls for overinterpretation as pleomorphic sarcoma, which would appear to be inappropriate in most cases. Due to its rarity and uncertainty, we report a case of atypical fibrous histiocytoma and discuss its presentation, nature, types and treatment with reference to a brief review of literature.

Reactive epithelial hyperplasia is a well-known phenomenon which occurs adjacent to certain neoplasms such as cutaneous fibrous histiocytoma, granular cell tumor, Spitz nevus, and melanoma. We report 46 cases of paratumoral follicular and epidermal hyperplasia associated with basal cell carcinoma (BCC). This reactive process associated with BCC has certain characteristic features. It is focal, superficial, and predominantly folliculocentric. It may resemble other tumors such as squamous cell carcinoma and may appear in sections where BCC is absent. The recognition of this entity may help dermatopathologists avoid misdiagnosing this process as a tumor and can suggest further search (section through the block or rebiopsy) when this reactive phenomenon is seen in sections without the associated BCC.

Background: Ulceration and osteoclast-like giant cells are two pathological features uncommonly seen in dermatofibromas. To our knowledge, the presence of these features has not been previously described within the same lesion. Methods: We report the clinical, histopathological and immunohistochemical findings of a 38-year-old man with an ulcerated dermatofibroma (DF) on the sole containing OLGC. Comments: DF, or cutaneous fibrous histiocytoma, is a frequent dermatological lesion with many clinicopathological variants. Therefore, a correct diagnosis is not always straightforward, especially when two rare features co-exist in the same lesion. Differential diagnosis was performed with cutaneous and even non-cutaneous lesions. An explanation for the clinicopathological findings is also described.

This is a report of a previously undescribed type of histiocytoma distinguished clinically by its occurrence as a solitary elevated nodule often with a vascular appearance and cytologically by the presence of large angulated epithelioid cells. Nineteen lesions from 11 women and eight men have been studied. The lower limb was the commonest site for the nodules. The mean age at presentation was 42 years (range 23-63). Only one lesion recurred after attempted removal. This lesion in the past may, have been mistaken for a Spitz naevus. Immunohistochemical findings mirror those of ordinary histiocytomas. In particular approximately 50% of the constituent cells label with a polyclonal antibody directed against factor XIIIa--an antibody that labels dermal fixed connective tissue cells (fibrocytes) and cells in ordinary histiocytoma, but not the cells of Spitz or common melanocytic naevi.

Atypical cutaneous fibrous histiocytoma is a rare variant of dermatofibroma/fibrous histiocytoma characterized by striking atypia, thus resembling atypical fibroxanthoma. We studied 9 examples of ACFH histopathologically and immunohistochemically to investigate the nature of these atypical cells. Histology revealed ill-defined skin nodules, which were polypoid in 6 cases. A minority of mononuclear and giant cells (< 5%) revealed striking pleomorphism and showed large nuclei with prominent nucleoli. Immunohistologically, the atypical cells expressed vimentin, but were negative for S-100 protein, the keratin marker MNF116, alpha smooth muscle actin, CD34, factor XIIIa, and monocyte/macrophage markers Ki-M1p, KP1 (CD68), and MAC387. Positivity for MiB1 was very modest (< 1%) and limited to small- and medium-sized, inconspicuous cells. Multinucleate giant cells proved to be heterogenous, on one hand cells with differentiation toward macrophages with positivity for Ki-M1p and KP1, on the other toward fibroblasts positive for vimentin only. These immuno-histochemical results for differentiation markers in atypical cutaneous fibrous histiocytoma are similar to our previous findings and data in atypical fibroxanthoma; MiB1 helps to separate these entities from each other as the latter shows a very high proportion of proliferative atypical cells corresponding to the numerous mitoses seen in routine sections.

Benign fibrous histiocytoma is a common soft tissue tumor that can be deep or superficially located. Although the deep type of fibrous histiocytoma has a predilection for the orbit, the eyelids are an unusual location for the cutaneous type. A 42-year-old woman had bilateral yellowish nodular masses of the eyelids for two years. Pathological examination after excision revealed benign fibrous histiocytoma. Our case is an unusual clinical presentation of cutaneous fibrous histiocytoma as well as a rare location such as the eyelids.

Epithelioid benign fibrous histiocytoma, also known as 'epithelioid cell histiocytoma,' has traditionally been considered a morphologic variant of cutaneous fibrous histiocytoma (dermatofibroma). In addition to its characteristic epithelioid cytomorphology, several phenotypic differences suggest that epithelioid fibrous histiocytoma may differ biologically from other variants. Recently, ALK rearrangement was described in two cases of epithelioid fibrous histiocytoma and separately in two cases reported as 'atypical' fibrous histiocytoma (with epithelioid features), with corresponding ALK expression detectable by immunohistochemistry. The goals of this study were to determine the frequency of ALK expression by immunohistochemistry in epithelioid fibrous histiocytoma, to determine its value for the diagnosis of epithelioid fibrous histiocytoma among variants and other histologic mimics, and to evaluate ALK gene rearrangement in epithelioid fibrous histiocytoma. ALK protein expression was evaluated in whole tissue sections from 33 epithelioid fibrous histiocytomas, 41 other cases of fibrous histiocytoma (11 conventional and 10 each cellular, atypical, and aneurysmal types), 10 cutaneous syncytial myoepitheliomas, and 5 atypical fibroxanthomas, using a mouse anti-ALK monoclonal antibody. Fluorescence in situ hybridization (FISH) was performed using break-apart probes. In total, 29/33 (88%) cases of epithelioid fibrous histiocytoma showed diffuse cytoplasmic ALK expression. Staining was moderate to strong in intensity in all cases except one, which showed diffuse weak expression. All other tumor types were negative for ALK expression. FISH demonstrated ALK rearrangement in all ALK-immunoreactive cases evaluated (n=13), and not in one ALK expression-negative epithelioid fibrous histiocytoma successfully examined. In conclusion, the majority of epithelioid fibrous histiocytomas demonstrate ALK expression and ALK gene rearrangement. ALK expression is not seen in other variants of fibrous histiocytoma, providing a useful diagnostic tool to distinguish epithelioid fibrous histiocytoma from most histologic mimics. The expression of ALK suggests that epithelioid fibrous histiocytoma is a biologically distinct tumor type, unrelated to conventional fibrous histiocytoma and histologic variants.

Background: Dermatofibroma (DF) or cutaneous fibrous histiocytoma is a common benign fibrohistiocytic lesion involving the dermis and subcutis. Histologically, it is subclassified into fibroblastic and histiocytoid forms. Its histogenesis is controversial. While often referred to as a neoplastic process, definite evidence of neoplasia in DF has been lacking. Alternatively, some authorities have suggested that DF is a fibrosing inflammatory process. Diagnostically, the most important question faced is the distinction from dermatofibrosarcoma protuberans (DFSP). Misdiagnosis can occur, as the early phase of DFSP can simulate DF, particularly the deep and cellular forms of DF. Methods: To address this issue, and to investigate whether DF is in fact a neoplasm, we evaluated 31 examples of DF of various histological types in female patients and assessed clonality by analyzing X-chromosome inactivation as indicated by the methylation status of the androgen receptor gene (HUMARA). Representative cases of DFSP were analyzed for comparison. Results: Among the selected 31 cases of DF, 24 cases provided intact DNA and informative polymorphism at the AR alleles, including one case of recurrent deep fibrous histiocytoma. Among these 24 cases, randomly inactivated AR alleles were observed in 17 cases including a deep, recurrent fibroblastic DF. A non-random inactivation at AR alleles was observed in seven cases, of which six cases showed either typical histiocytoid form of DF (four cases) or mixed cell types with predominant histiocytoid cell type (two cases). One fibroblastic DF also showed a monoclonal pattern. HUMARA analysis of DFSP revealed non-random inactivation of polymorphic AR alleles. Conclusions: These findings suggest that DF is a heterogeneous process. Monoclonal genotype was found in DFs with histiocytoid or mixed type with predominant histiocytoid features, suggesting that histiocytoid cells probably represent the neoplastic component. The fibroblastic form of DF may represent a reactive fibroblastic proliferation. Alternatively, it may represent a true neoplasm whose neoplastic cell type has been obscured by prominent reactive fibroblastic component.

We report on eight cases of a distinct variant of cutaneous schwannoma characterized by prominent Verocay body formation (75-100% of the tumor bulk) that may cause considerable diagnostic difficulties. Like ordinary cutaneous schwannomas, these lesions preferred the head and neck region of young adults without sexual predilection and were clinically interpreted as cyst, basal cell carcinoma, or nevus. Histological examination revealed well-circumscribed nodules. Three of them consisted exclusively of nodular or ribbon-like Verocay bodies. A variable admixture of Antoni A or B type of differentiation (< 25%) was seen in five other cases. The following patterns were seen: fascicular spindle-shaped, onion-like epithelioid, myxoid-hypocellular, and degenerated ("ancient") with prominent fibrosis/hyalinosis and occasional bizarre giant cells. Immunohistochemically, the lesions were positive for S-100 protein (and vimentin) but negative for a broad panel of neurogenic and intermediate filament markers. The capsule showed focal labeling for EMA and--when it was markedly thickened--also for SMA. Labeling with E9, an anti-metallothionein marker indicative of cell activity, was negative, underscoring the slow growth potential of these lesions. No recurrence was seen in the six patients with follow-up information. The differential diagnosis includes other lesions with prominent palisading. (Amianthoid) myofibroblastoma and palisading leiomyoma are consistently positive for SMA and desmin, respectively. Palisading cutaneous fibrous histiocytoma and myofibroblastic dermatofibroma are variably positive for Factor XIIIa, SMA, and E9 and/or NK1C3 (CD57). Palisaded encapsulated neuromas are primarilly differentiated by the presence of nerve fibers with myelin sheaths.

Recently, a distinct variant of cutaneous fibrous histiocytoma (FH) has been histologically characterized as a "cellular" subtype. This variant is often mistaken for sarcoma, including dermatofibrosarcoma protuberans. We report a case of cellular FH of the skin in which the cytogenetic analysis demonstrated a novel chromosome pattern, possibly allowing distinction from its histologic simulants.

Atypical fibrous histiocytoma (AFH) is an uncommon variant of cutaneous fibrous histiocytoma that can display histologic features associated with malignancy. Fewer than 150 cases have been reported in the literature. The majority of these lesions present on the trunk and extremities of middle-aged women. Genital lesions are rare, with one documented case of vulvar AFH and another case of scrotal AFH in the literature. We report an additional case of a 68-year-old woman who was diagnosed with an AFH in an unusual location, the perianal area. Histologically, the lesion was characterized by a nodular fairly well-circumscribed proliferation of large epithelioid macrophages with scattered lymphocytes and mast cells in the background. The atypical macrophages contained enlarged markedly pleomorphic nuclei with prominent nucleoli. Scattered multinucleated "monster cells" and atypical mitoses were observed throughout the lesion. Immunologically, the lesional cells were focally positive when stained with antibodies against CD163 and Factor XIIIa. They were negative for CD34, CD31, desmin, smooth muscle actin, CAM 5.2, keratin 5/6, S100, CD3, CD20, and CD30. The constellation of histologic and immunologic features was most consistent with an AFH. To our knowledge, this case is the first perianal presentation of AFH to date.

Background: Reactive hyperplasia can occur in any part of the body but of concern is occurrence adjacent to certain neoplasm such as cutaneous fibrous histiocytoma, granular cell tumor, spitz nevus and melanoma. Ocular reactive epithelial hyperplasia is not as common as ocular reactive lymphoid hyperplasia. This is the first reported case in our environment. The patient was concerned about his cosmetic appearance, comments of friends and fear of eye problem in future. We report the case of a 32 year old patient with painless, progressive swelling of the conjunctiva following stone injury to the eye while on a bike 5 years earlier. A traumatic conjunctival cyst to rule out melanoma was the initial diagnosis. We therefore, managed the case by excision biopsy and histology report was in keeping with conjunctival reactive epithelial hyperplasia. One year after removal, he was free of any swelling and had no complaints. Conclusion: Excision biopsy is effective and it will assist in ruling out neoplasm and taking care of the patient’s cosmetic problem.

Cutaneous fibrous histiocytoma (FH) is considered a benign tumor; however, certain types of FH have been shown to have a tendency for local recurrence, and there are rare reported cases of metastasis. In this study, 16 cases of morphologically benign FH with locoregional or distant metastasis were identified in consult files. Pathologic features of primary, recurrent, and metastatic tumors, as well as clinical outcome, were evaluated. Nine were male and 7 were female patients; mean age was 42 years (range, 3 to 68 y). Primary tumors arose on the leg in 5 patients, buttock in 1, trunk in 3, shoulder in 3, neck in 2, and finger in 1. The primary site in 1 case was unknown. Fifteen primary tumors available for review involved the dermis; 6 extended into the superficial subcutis. Tumor size ranged from 1 to 5 cm (median 3.2 cm). Histologically, primary tumors showed characteristic features of FH, being composed in most cases of a polymorphous population of bland spindle and histiocytoid cells in a mixed storiform and fascicular growth pattern with admixed foam cells, multinucleate cells, and inflammatory cells in varying proportions. Histologic variants included 11 cellular (2 with mixed atypical and cellular features), 2 aneurysmal, 1 atypical, and 1 epithelioid type. All tumors showed entrapment of hyalinized collagen bundles. Mitotic activity ranged from

Dermatofibroma (cutaneous fibrous histiocytoma) represents a common benign mesenchymal tumor, and numerous morphological variants have been described. Some variants of dermatofibroma are characterized by an increased risk of local recurrences, and there are a few reported metastasizing cases. Unfortunately, an aggressive behavior cannot be predicted reliably by morphology at the moment, and we evaluated the value of array-comparative genomic hybridization (CGH) in this setting. Seven cases of clinically aggressive dermatofibromas were identified, and pathological and molecular features were evaluated. The neoplasms occurred in four female and in three male patients (mean age was 33 years, range 2–65 years), and arose on the shoulder, buttock, temple, lateral neck, thigh, ankle, and cheek. The size of the neoplasms ranged from 1 to 9 cm (mean: 3 cm). An infiltration of the subcutis was seen in five cases. Two neoplasms were completely excised, whereas an incomplete or marginal excision was reported in the remaining cases. Local recurrences were seen in six cases (time to the first recurrence ranged from 8 months to 9 years). Metastases were noted between 3 months and 8 years after diagnosis in six patients. Two patients died of disease, and two patients are alive with disease. Histologically, the primary tumors showed features of cellular dermatofibroma (four cases), cellular/aneurysmal dermatofibroma (one case), atypical/cellular dermatofibroma (one case), and classical dermatofibroma (one case). Mitotic figures ranged from 3 to 25 per 10 high-power fields, and focal necrosis was present in five cases. Interestingly, malignant transformation from cellular dermatofibroma to an obvious spindle cell/pleomorphic sarcoma was seen in one primary and in one recurrent neoplasm. Five neoplasms showed chromosomal aberrations by array-CGH, suggesting that these changes may represent an additional diagnostic tool in the recognition of cases of dermatofibroma with a metastatic potential.

Dermatofibroma, also called cutaneous fibrous histiocytoma or sclerosing hemangioma, is a fairly common, benign cutaneous tumor. Polypoid dermatofibroma is an unusual and poorly recognized form of this entity. We describe a peculiar case of this variant presenting with a unique morphology characterized by a round flat shape with a slim pedicle, although its histopathological picture was rather typical of that of ordinary dermatofibroma.

We report seventy-four cases of a distinctive variant of cutaneous fibrous histiocytoma, which is often mistaken histologically for sarcoma and which carries a high local recurrence rate. These tumors appeared most commonly in young or middle-aged adults, with a predominance in men (male/female ratio 1.9:1). Anatomic distribution was wide, with cases occurring mainly in the upper limb/limb girdle (34%), lower limb/limb girdle (27%), and head and neck region (20%). Most lesions had been present for only a few months, and their sizes ranged from 0.5 cm to 2.5 cm in maximum diameter. Twelve (26%) of 46 cases with follow-up (mean duration 3 years) recurred locally, in one case twice. Distinctive histologic features were a commonly fascicular growth pattern, predominance of eosinophilic spindle cells with tapering nuclei, a moderate mitotic rate (mean three per 10 high-power fields), and frequent extension into the subcutaneous fat (33% of cases). In addition, all cases showed at least focal cytologic polymorphism (inflammatory cells, foam cells, giant cells), and 58% showed associated epidermal alterations in common with usual cutaneous fibrous histiocytomas. Nine cases (12%) showed foci of central necrosis. Immunohistochemical studies (ABC method) found only vimentin and very focal smooth muscle actin positivity. Tests for CD34, desmin, S-100, keratin, and Factor XIIIa were negative in all cases. These lesions should be distinguished from dermatofibrosarcoma protuberans and leiomyosarcoma, with which many of these cases were initially confused.

Dermatofibroma (DF), also referred to as cutaneous fibrous histiocytoma (CFH), is a common tumor of the skin presenting as a firm nodule located predominantly on the limbs and shoulder and pelvic girdles that often extends into superficial subcutaneous tissue. This is a retrospective study of 26 DFs located on digits. All case slides were retrieved from saved files for diagnostic verification. One case was rejected after revision of the diagnosis to giant cell tumor of the tendon sheath. The 26 remaining cases constitute this reported series. Digital DFs affected 27 to 70 year-olds in a 2.25:1 male to female ratio. The most common clinical diagnosis submitted was "growth" or wart. In only 6 out of the 26 cases was the pre-biopsy diagnosis of DF ventured. Although lesional tissue went to dermal margins in 14 specimens, only one has been re-excised in follow up ranging from 2 months to 10 years. Because DFs can resemble several entities including leiomyosarcoma and dermatofibrosarcoma protuberans, a lack of familiarity with the occurrence of DF on the digits may result in more aggressive treatment than otherwise necessary. DF should be in the differential diagnosis of circumscribed, firm nodules presenting on the digits.

Background: Epithelioid fibrous histiocytoma (EFH) represents a morphologic variant of cutaneous fibrous histiocytoma (FH) but can lack many characteristic features. The presence of epithelioid cytomorphology may mimic other dermal neoplasms. Our anecdotal experience of epithelial membrane antigen (EMA) expression in some examples of EFH has caused diagnostic difficulty. Our aim was to examine the immunohistochemical profile and incidence of EMA expression in EFH. Methods: Forty-four cases of EFH were retrieved from consultation files. Clinicopathologic and immunohistochemical features were evaluated. Results: Membranous EMA positivity was found in tumor cells in 27/42 cases (64%). Focal positivity for factor XIIIa was found in 10/14 (71%) and D2-40 in 14/27 (52%). Scattered smooth muscle actin (SMA)-positive tumor cells were seen in 11/43 (25%). Focal positivity for claudin-1 was found in 3/42 (7%). CD163 staining highlighted stromal macrophages; however, in five cases it was difficult to exclude focal staining of tumor cells. Tumor cells were consistently negative for pan-keratin, AE1/AE3, S100, CD31, CD34, CD68, desmin, p63, GFAP and CD45/LCA. Conclusion: Frequent EMA expression in EFH represents an unexpected finding and constitutes a potential diagnostic pitfall. Although of uncertain significance, this finding, when combined with established morphologic differences, raises the possibility that EFH is unrelated to classic FH. Doyle LA, Fletcher CDM. EMA positivity in epithelioid fibrous histiocytoma: a potential diagnostic pitfall.

CD163, a hemoglobin scavenger receptor, is expressed in monocytes and macrophages. Recent work has shown that this marker is specific for neoplasms of histiocytic differentiation. Our aim was to test the ability of CD163 to separate cutaneous histiocytomas from their morphologic mimics. We tested the expression of CD163 in 78 cases, including 19 xanthogranulomas, 16 atypical fibroxanthomas, 6 reticulohistiocytomas, 8 epithelioid cell histiocytomas, 9 cases of Langerhans cell histiocytosis, 10 xanthomas, and 10 intradermal Spitz nevi. CD163 expression was seen in all xanthogranulomas and reticulohistiocytomas, 4 epithelioid cell histiocytomas, 2 cases of Langerhans cell histiocytosis, and 8 xanthomas but was absent in atypical fibroxanthomas and Spitz nevi. CD163 is an excellent marker for confirming histiocytic differentiation and is useful in eliminating morphologic mimics such as Spitz nevi from the differential diagnosis. The lack of CD163 in atypical fibroxanthomas argues against a histiocytic origin for this tumor.

Dermatofibroma (DF), or cutaneous fibrous histiocytoma, is a common cutaneous tumor with many variants that may arise from alterations in the morphology and composition of its various components. One type that has not received much attention is DF with osteoclast-like giant cells. Two cases of this rare tumor are described. The importance of this tumor lies in the possible histologic confusion with a variety of benign and malignant neoplasms, including giant cell tumor of tendon sheath, giant cell tumor of bone, and giant cell reparative granuloma.

Dermatofibroma or cutaneous fibrous histiocytoma is a common benign skin lesion with multiple, distinct histologic variants, including cellular, aneurismal, epithelioid, atypical, lipidized "ankle-type," palisading, and cholesterotic. Although dermatofibromas are considered benign neoplasms, certain variants including cellular and aneurismal ones have shown to have a notable tendency to locally recur after excision. Indeed, although extremely rarely, metastases have been associated with the cellular and aneurysmal/atypical variants. Signet-ring cells are formed by cytoplasmic accumulations of various substances that push the nucleus toward the cellular border. The finding of signet-ring cells in a skin neoplasm always raises the suspicion of metastatic adenocarcinoma, although a number of reports have shown their occurrence in primitive cutaneous neoplasms as well. Signet-ring cell formation, however, has never been described in dermatofibroma. We present, for the first time, a new, distinctive variant of dermatofibroma, so-called signet-ring cell dermatofibroma, in a 16-year-old man with a slowly growing skin tumor on the lateral side of his right leg. Histologic examination demonstrated a striking signet-ring cell appearance of most of the cells in an otherwise fibrohistiocytic looking proliferation. Histochemical and immunohistochemical stainings confirmed the diagnosis of dermatofibroma. The phenomenon described in this case enlarges the histologic spectrum of cutaneous fibrous histiocytoma and may cause substantial differential diagnostic problems.

Aneurysmal fibrous histiocytoma (AFH) (Santa-Cruz DJ, Kyriakos M. Aneurysmal (‘Angiomatoid’) fibrous histiocytoma of the skin. Cancer 1981;47:2053–2061) is a distinct but poorly recognized clinicopathological variant of cutaneous fibrous histiocytoma (CFH) that may result from the slow extravasation of blood into the tumour. The resulting lesion can have a very different clinicopathological appearance resulting in diagnostic confusion. We describe a patient with an AFH that presented as a pigmented nodule on the foot and discuss clinical recognition and histological differentiation from other tumours.

Dermatofibroma (DF) or cutaneous fibrous histiocytoma is a common benign skin tumor that exhibits multiple, distinct histologic variants. Although clear cell DF has been described in the literature, balloon cell degeneration causing a clear cell DF phenotype has been not been reported to date. Herein, we describe the clinicopathologic findings of balloon cell DF arising on the heel of a 43-year-old man. Clinically, it presented as enlarging tan-white, ulcerated, firm 1.5 cm nodule, clinically suspected to be pyogenic granuloma. Excisional biopsy revealed a circumscribed fibrous tumor populated by mostly clear and spindle cells. A zonal arrangement separated the varied tumor cells where the most superficial, polypoid area showed large, clear polygonal balloon cells; the mid-dermal zone demonstrated a transition between balloon cells, epithelioid cells, and spindle cells; and the deep dermal zone had storiform arrangement of spindle cells, with the fascicles separated by coarse collagen bundles. A CD10+ > CD68+ > Factor XIIIa+ immunophenotype was identified with negative immunolabeling for S-100 protein, HMB-45, cytokeratin AE1/AE3, desmin, smooth muscle actin, lysozyme, and leukocyte common antigen (LCA). Ultrastructurally, the clear tumor cells were filled with multiple, empty, nonmembrane bound vacuoles of varying size. No recurrence has been described after complete excision and 7 months of follow up. DF with balloon cell change, likely secondary to persistent irritation, should be added to the differential diagnosis of cutaneous primary and metastatic neoplasms showing balloon cell degeneration such as balloon cell melanocytic nevi and renal cell carcinoma, respectively.

Cutaneous fibrous histiocytomas are usually regarded as superficial lesions and commonly known as dermatofibromas; however, unusual cases histologically showing fibrohistiocytic proliferation extending into the deeper dermis or subcutaneous tissues are occasionally experienced. Some authors propose this type as benign fibrous histiocytoma of the skin, distinct from dermatofibroma. We describe herein a case of systemic lupus erythematosus (SLE) who developed multiple nodules on the face, trunk and extremities. The nodule on the forehead did not present a typical clinical appearance of dermatofibroma, and histopathological examination showed fibrohistiocytic proliferation with a storiform pattern extending into the deep dermis and subcutaneous tissues. By contrast, histology of the nodule on the abdomen showed fibrohistiocytic proliferation confined to the dermis and compatible with dermatofibroma. Although multiple dermatofibromas are occasionally seen in patients with SLE, benign fibrous histiocytoma of the skin showing deeper invasion than dermatofibroma is rarely associated with SLE.

We present the case of a 53 years-old woman presenting with congestive heart failure and pleural and pericardial effusions, in whom transthoracic and transesophageal echocardiography revealed multilocular cardiac tumor involving the left atrium wall, extending into the pericardium. Tumor was excised surgically and proved to be a malignant fibrous histiocytoma, primarily confined to the heart. Despite surgery followed by chemotherapy, the patient died a few months later. This is the 47th case of primary cardiac fibrous malignant histiocytoma reported in the literature. The pericardial involvement has been only rarely reported. Echocardiography was the method of diagnosis before rapid referral to surgery.