Atypical Fibroxanthoma With Osteoclast-Like Giant Cells: A Report of a Rare Histopathological Entity and Review of the Literature

Atypical fibroxanthoma, a malignant fibrohistiocytic tumor in the dermis, is considered to be a superficial version of the more aggressive pleomorphic dermal sarcoma.It occurs primarily in sun-exposed areas, particularly the head and neck region of elderly individuals.Surgical excision, especially with Mohs micrographic surgery, is generally curative.Atypical fibroxanthoma may exhibit a range of histopathologic features.It classically demonstrates pleomorphic cells arranged in a spindle pattern; in addition, atypical epithelioid cells with mitoses are commonly present.Additional microscopic features may also include granular areas, hemorrhage, keloid-like areas, myxoid change, and pseudoangiomatous features.Atypical fibroxanthoma with osteoclast-like giant cells is an exceedingly rare entity.In this paper, we present a 79year-old Caucasian woman who developed a rapidly growing ulcerated nodule on the right lateral eyebrow and adjacent right upper eyelid.A shave biopsy revealed a malignant dermal tumor with not only numerous osteoclast-like giant cells but also atypical spindle cells with hyperchromatic nuclei and occasional mitotic figures in the background.Immunohistochemical stains were performed and demonstrated positive staining of the tumor cells for cluster of differentiation 10 (CD10) and cluster of differentiation 68 (CD68); the osteoclast-like giant cells also showed positive staining for CD68.The tumor cells did not stain with S100, SRY-related HMG-box 10 (SOX-10), Preferentially Expressed Antigen in Melanoma (PRAME), cytokeratin AE1/AE3, and cytokeratin 5/6 stains.Correlation of the clinical presentation, histopathology, and immunohistochemical findings established the diagnosis of an atypical fibroxanthoma with osteoclast-like giant cells.The tumor was excised via the Mohs micrographic technique, and clear margins were obtained after the first stage; the resulting defect extended to superficial muscular fascia and was repaired with a local advancement flap.We report a patient with a rare variant of atypical fibroxanthoma presenting with osteoclast-like giant cells and review the literature regarding this uncommon entity.