Abstract
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.
Highlights
Aneurysmal fibrous histiocytoma (AFH) is a rare variant of benign fibroushistiocytoma (FH), posing diagnostic difficulty due to morphological resemblance to malignant melanoma, angiomatoid fibrous histicytoma, kaposi sarcoma and angiosarcoma
We report a case of aneurysmal benign fibrous histiocytoma with atrophic features in a 23-year-old male who presented with a pigmented papillomatous lesion in the leg
Histopathological findings show a tumor mass in the dermis that is composed of fibroblast-like spindle cells and histiocytes.(4).AFH is one of the rarest variants of cutaneous fibrous histiocytoma with reported incidence of 1.7% of all cutaneous fibrous histiocytoma(5).It was first described by Santa Cruz and Kyriakos in 1981(4)(6).AFH
Summary
Aneurysmal fibrous histiocytoma (AFH) is a rare variant of benign fibroushistiocytoma (FH), posing diagnostic difficulty due to morphological resemblance to malignant melanoma, angiomatoid fibrous histicytoma, kaposi sarcoma and angiosarcoma. Since AFH has a benign course but higher recurrence rate than FH(1) it is essential to differentiate it from the other close differentials This tumor accounts for less than 2% of all fibrous histiocytomas, and it is typically known to occur in the extremities of middleaged patients(2)(3). In addition to the typical features of a dermatofibroma, it contains large cleft-like or cavernous blood-filled spaces with numerous hemosiderin pigments. We report a case of aneurysmal benign fibrous histiocytoma with atrophic features in a 23-year-old male who presented with a pigmented papillomatous lesion in the leg. Section studied showed skin with epidermis, dermis and subcutaneous tissue. Upper dermis showed a well circumscribed lesion exhibiting focal storiform pattern (Fig.4) and composed of proliferating spindle shaped cells and macrophages containing hemosiderin pigments (Fig.[2]). A final diagnosis of Dermatofibroma – Aneurysmal Variant was given
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