Angiomatoid fibrous histiocytoma: staging and evaluation of response to therapy with F-18 FDG PET/CT.

摘要

Angiomatoid fibrous histiocytoma is a very rare tumor that accounts for 0.3% of all soft-tissue tumors, and occurs predominantly in the extremities of adolescents and young adults. It has been classified by the World Health Organization as a tumor of uncertain differentiation with intermediate malignant potential, although recent evidence suggests a myoid or myofibroblastic cell origin. Most examples behave in an indolent manner with a regional recurrence rate of 15% and a rate of metastasis of 1%. We present a 29-year-old woman who was referred for an F-18 FDG PET/CT to evaluate a left shoulder mass. She had multiple local FDG-avid lymph nodes, and initial biopsy was suggestive of epithelioid sarcoma. She was treated with chemotherapy, but a post-therapy PET/CT showed minimal response and radical surgical excision was performed. The histopathology and immu-nohistochemistry was consistent with angiomatoid fibrous histiocytoma. This case highlights a potential new utility for F-18 FDG PET/CT in the staging and evaluation of response to therapy for this very rare soft-tissue tumor.