Superficial CD34-positive fibroblastic tumor: A new case from Japan.

A 48-year-old Japanese woman presented with a painless, slow-growing, brown nodule of 15 mm in diameter on the left thigh. She noticed the nodule a few years before the first presentation to our hospital. She underwent total resection of the nodule. On histopathological examination, a relatively well-defined tumor with infiltrative growth was located in the dermis and extended into the subcutis. The tumor was composed of spindle to polygonal cells with pleomorphic nuclei arranged in a sheet-like or fascicular pattern. Tumor cells with granular cytoplasm were also scattered. Immunohistochemical examination revealed that the tumor cells were strongly positive for CD34. The fusion transcripts of the collagen type 1 alpha 1 platelet-derived growth factor beta chain were not detected. After excluding other fibroblastic tumors through histopathological and immunohistochemical examinations, a diagnosis of superficial CD34-positive fibroblastic tumor (SCPFT) was made. SCPFT is a recently proposed fibroblastic tumor that is characterized by striking pleomorphism, granular cytoplasm, low mitotic rate and diffuse CD34 expression. Only two reports with 20 cases have been reported so far. The present case is the first that corresponds to SCPFT in Japan.