fibromyxoid tumor; ossifying fibromyxoid tumors; OFMT; subcutaneous tumor; desmin positivity; ossifying fibroma; fibroma; ossifying; soft tissue neoplasms


Dermatology | Pathology


The following case study demonstrates a 26-year-old male that presented to the dermatology clinic with an enlarging, raised skin nodule located on the left inferior lateral lower back. The patient reported it had persisted for two years, and he had not received prior treatment. He noted a family history of nonmelanoma skin cancer but had no other dermatological issues in the past. Physical examination revealed a pink, firm and well-circumscribed subcutaneous mass with a prominent follicular pore. It was assumed the lesion was an epidermal inclusion cyst, and surgical excision was performed. Histopathology revealed lobules of epithelioid cells with indistinct cytoplasm in a fibromyxoid hyalinized matrix surrounded by lamellar bone and a collagenous pseudocapsule. Immunohistochemical staining showed moderate desmin immunoreactivity and negative immunoreactivity for CD34, S-100, EMA, actin and pancytokeratin. Based on the findings, a diagnosis of ossifying fibromyxoid tumor was made. Given the uncertain biological potential of this lesion, re-excision was performed. No residual tumor was identified on repeat pathological evaluation. The patient was scheduled for close follow-up to survey for recurrence or possible metastasis.

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Image 1: Clinical Image demonstrating a 2.3cmx2.0cm subcutaneous nodule.

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Image 2: H&E at 10x demonstrates lobules of epithelioid cells set within a fibromyxoid matrix surrounded by a "partial shell" of lamellar bone as well as a collagenous pseudocapsule.

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Image 3: H&E at 100x demonstrates relatively monomorphous, epithelioid cells with indistinct cytoplasm set within a fibromyxoid to hyalinized matrix. Neither atypical mitotic activity nor necrosis was identified.

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Image 4: Desmin Immunoreactivity.