Superficial CD34-positive fibroblastic tumor with locoregional metastasis: a case report

Superficial CD34-positive fibroblastic tumor (SCD34FT) and PRDM10-rearranged soft tissue tumor are mesenchymal neoplasms of intermediate malignancy increasingly recognized as the same entity. They typically arise in superficial soft tissues and behave indolently, with a low risk of local recurrence and rare regional metastasis. We describe a SCD34FT in a 48-year-old man with a right triceps mass that underwent neoadjuvant radiation and resection. Within a year, he developed metastasis to the right ninth rib that slowly grew over 6 years. The tumors showed pleomorphic epithelioid and spindled cells in myxoid stroma, prominent nucleoli, scattered bizarre nuclei with smudgy chromatin, in keeping with SCD34FT. Molecular analysis identified a CITED2::PRDM10 fusion. Following radiation and resection of the metastasis, the patient remained disease-free at 1 year. This case provides another example of SCD34FT that developed locoregional metastasis to the literature and supports its known biologic behavior as an indolent but rarely metastasizing neoplasm.