Cutaneous Fibrous Histiocytoma Research Articles

Granular cell dermatofibroma: A potential diagnostic pitfall.

Dermatofibroma, also known as “fibrous histiocytoma”, is one of the most common cutaneous soft-tissue tumours. Many variants of dermatofibromas have been described and knowledge of these variations is important to avoid a misdiagnosis of a possibly more aggressive tumour. 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 a correct nosographic classification. We report on the case of a cutaneous fibrous histiocytoma, “granular cell” variant, found on the left leg of a 74- year-old woman.

Cutaneous Fibrous Histiocytomas, Ossifying-Variant with Osteoclast-like Giant Cells and Granular Cell-Variant: A Series of Two Unusual Cases with Emphasis on the Differential Diagnosis

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.

Granular Cell Dermatofibroma: When Morphology Still Matters

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.

Aneurysmal pinna – An unfamiliar entity

Lesions ranging from cysts to benign and malignant tumors can affect the pinna. The clinical appearance, duration, progression, and histopathology of the lesion are important in differentiating non-neoplastic conditions from neoplasms. We present a case report of an unusual nodular pinna lesion that was excised under local anaesthesia. Histopathology revealed cutaneous aneurysmal fibrous histiocytoma. Aneurysmal benign fibrous histiocytoma is an unusual variant of soft tissue tumor with low intermediate malignant potential, which has to be differentiated from other benign and malignant tumors.
 Keywords: Benign fibrous histiocytoma; external ear; fibrous tissue neoplasms.

Aneurysmal Fibrous Histiocytoma: A Rare Variant

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.

A Clinicohistopathological Analysis of Cutaneous Fibrous Histiocytomas of the Finger.

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.

Giant Fibrous Histiocytoma : Clinical and Dermoscopic Features

Benign fibrous histiocytoma is one of the most frequent benign neoplasms ,the diagnosis of cutaneous benign fibrous histiocytoma is generally easy ,however the atypical fibrous histiocytoma is an uncommon, poorly documented variant of cutaneous fibrous histiocytoma,may be difficult to identify, and the diagnosis only confirmed after exhaustive histopathological examination. Recently the dermoscopy has revealed a new dimension of dermoscopic features giant Fibrous Histiocytoma . Our purpose was to report the clinical and dermoscopic characteristics of giant Fibrous Histiocytoma and review the few cases of this variant of Fibrous Histiocytoma reported in the literature.

Aneurysmal Fibrous Histiocytoma: Clinicopathology Analysis of 30 Cases of a Rare Variant of Cutaneous Fibrohistiocytoma.

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.

Anterior abdominal wall spindle cell tumour - atypical fibrous histiocytoma: a rare presentation

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.

Epithelioid fibrous histiocytoma: molecular characterization of ALK fusion partners in 23 cases

AbstractEpithelioid 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.

Dermoscopic findings in an early malignant fibrous histiocytoma on the face.

Malignant fibrous histiocytoma (MFH), currently classified as undifferentiated pleomorphic sarcoma, is the most frequent soft tissue sarcoma in adulthood, but it is not as common as a primary skin tumor. MFH affects mostly the thighs and trunk, head and neck is an infrequent presentation in adults. MFH is often diagnosed in advanced stages, with a tendency to local recurrence and systemic metastasis. Since tumor thickness and size are identified as major prognostic factors, early recognition becomes crucial to improve prognosis. We present a case of a cutaneous malignant fibrous histiocytoma located on the face in which dermoscopy was useful in clinical management and definition.

Clinicopathologic analysis of four cases of desmoplastic melanocytic nevus

Objective To investigate pathological characteristics and differential diagnosis of desmoplastic melanocytic nevus. Methods Four cases of desmoplastic melanocytic nevus were analyzed based on the clinical manifestations and histological, immunohistochemical and fluorescence in situ hybridization (FISH) features. Results Of the 4 cases, 2 were male and 2 were female. Their age ranged from 19 to 30 years with the average age being 26.5 years. The skin lesions were located on the extremities in 3 cases, on the vulva in 1 case. Histologically, the lesions were bilaterally symmetrical intradermal nevus. Nevus cells appeared epithelioid and/or fusiform, some were clustered or scattered in the proliferative fibrous tissue. None of lymphocyte aggregation, necrosis or ulceration was observed. Immunohistochemical examination showed positive staining for S100 and Melan A in 3 cases, positive staining for P16 in 2 cases, Ki-67-labeling index less than 5% in all the 4 cases, and negative staining for factor XIII (FXIII) and CD34 in 2 cases. FISH assay showed no copy-number variations in gene loci 6p25 (RREB1) , 6q23 (MYB) , 6p11.1-q11.1 (Cep6) and 11q13 (CCND1) in desmoplastic melanocytic nevus. Conclusion Desmoplastic melanocytic nevus is a kind of histologically unique, benign melanocytic nevus, and immunohistochemical staining for Ki-67, S-100, Melan A and FⅩⅢand FISH assay on melanoma can be helpful for the differential diagnosis between cutaneous fibrous histiocytoma and melanoma. Key words: Nevus, pigmented; Pathologic processes; Skin manifestations; Immunohistochemistry; Desmoplastic melanocytic nevi; FISH

Conjunctival reactive epithelial hyperplasia in a black African patient- a case report

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.

ALK rearrangement and overexpression in epithelioid fibrous histiocytoma

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.

DNA copy number changes in tumors within the spectrum of cellular, atypical, and metastasizing fibrous histiocytoma

Cutaneous fibrous histiocytoma (FH) is a common mesenchymal neoplasm. Metastasis is rare, disproportionately occurring among the aneurysmal, cellular, atypical, and deep variants. 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). 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. 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. This study included a small sample size with a short-term follow-up. 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.

Atypical Fibrous Histiocytoma Arising in the Perianal Area

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.

Metastasizing “Benign” Cutaneous Fibrous Histiocytoma

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 <1 to 13/10 HPF. Focal necrosis was seen in 1 primary tumor. Ten patients had local tumor recurrence; 4 patients had multiple local recurrences. Time to first recurrence ranged from 6 weeks to 13 years. The local recurrences of 1 tumor showed increased cytologic atypia, but recurrences were otherwise morphologically similar to primary tumors. Metastases occurred 0 to 180 months after diagnosis (median 17 mo) and involved the lungs (12 patients), lymph nodes (8), soft tissues (6), and liver (1). Five patients developed multiple satellite nodules in the region of the primary tumor. Metastases were morphologically similar to the primary tumors. So far, 6 patients died of disease, with a median time to death of 64 months (range, 10 to 168 mo). Four patients are alive with metastatic disease. Two patients are disease free at last follow-up, and 1 patient died of unrelated disease. Metastasis of morphologically benign cutaneous FH is an extremely rare but clinically aggressive event. Primary tumors tend to be large and cellular, but aggressive behavior cannot be predicted on morphologic grounds alone; however, early or frequent local recurrence may warrant closer clinical follow-up.

Malignant dermatofibroma: clinicopathological, immunohistochemical, and molecular analysis of seven cases

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.

A case of cutaneous malignant fibrous histiocytoma with multiple organ metastases

Malignant fibrous histiocytoma is a soft tissue sarcoma that most commonly occurs in the extremities and rarely metastasizes cutaneously. A 79-year-old male patient consulted a dermatologist 11 months after recognizing an intractable ulcer on the right mandible. Punch biopsy revealed eosinophilic tumor cells in the dermal area and proliferation of rich spindle cells. Malignant fibrous histiocytoma or atypical fibroxanthoma was suspected and he was referred to our hospital. Red plaque tumors on the right mandible and right temple were 30 mm and 15 mm in size, respectively. The right mandible lesion was ulcerated. Immunohistochemically, the lesions were positive for CD10, CD74 and alpha-smooth muscle actin. Radiological analysis revealed multiple organ metastases, including bone, liver, lung and skin on the right temple. The patient was diagnosed with malignant fibrous histiocytoma, stage IV and died 8 weeks after the first visit due to respiratory failure. Cutaneous malignant fibrous histiocytoma has a poor prognosis resulting in death.

Desmin and CD34 positivity in cellular fibrous histiocytoma: an immunohistochemical analysis of 100 cases

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. One hundred consecutive cases of morphologically typical CBFH were retrieved from consultation files. Clinicopathologic and immunohistochemical features were evaluated. 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. 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.