A Rare Case of Superficial CD34+ Fibroblastic Tumor: A Case Report

A superficial CD34+ fibroblastic tumor (SCPFT) presents as a diagnostic conundrum due to its rarity and histologic similarity to other spindle cell neoplasms. SCPFT often presents as an inconspicuous, subcutaneous nodule with a predilection for the lower extremities in patients aged 20-40 years old. Herein, we describe a rare case of an SCPFT in a 61-year-old male who presented to the dermatology clinic for evaluation of a growth on his right neck that had been present for 5 years. On clinical examination, he had a well-circumscribed 1-cm mobile, subcutaneous nodule, suspicious for a lipoma. An excision was performed, and the specimen was sent for dermatopathology analysis which revealed a subcutaneous tumor composed of large, epithelioid to spindled, markedly pleomorphic cells with intranuclear pseudoinclusions and some with prominent nucleoli. Intermixed were large, atypical cells with ample bubbly cytoplasm, many of which contained hemosiderin, reminiscent of xanthomatous cells. Immunohistochemistry staining revealed strong and diffusely positive staining for CD34, vimentin, and CD10 with weak positivity for CD45 and CD68. Staining was negative for S100, PRAME, MART1, SOX10, AE1/3, desmin, STAT6, and p63. Given these findings, a diagnosis of SCPFT was made. SCPFT is a newly described entity in the family of CD34-positive spindle cell neoplasms and can be included in the differential for other pleomorphic soft tissue neoplasms. Given the low risk for local recurrence and metastasis of this tumor, complete surgical excision is mainstay. Our patient underwent successful surgical excision with negative margins and had no recurrence after one year.