Plexiform Fibrohistiocytic Tumor: A Rare Low‐Grade Myofibroblastic Tumor of Children and Young Adults

Abstract

We describe a 7‐year old male with a 7‐month history of a plexiform fibrohistiocytic tumor (PFT) presenting as an innocuous 0.5 × 0.5 cm nodule on the nasal dorsum. Following diagnostic sampling, Mohs’ micrographic surgery was performed to ensure adequate removal and patient continues to do well 1 year post‐surgery. PFT is a rare neoplasm described initially by Enzinger and Zhang in 1988. It afflicts children and young adults (median age: 14.5 years) and has a strong female predisposition. It typically occurs on the upper extremity. Histologically, the tumor has a bland appearance consisting of a biphasic population of varying numbers of fibroblast and histiocyte‐like cells. Cellular atypia and pleomorphism are lacking and mitotic activity is low. Immunohistochemically and ultrastructurally, the tumor demonstrates myofibroblastic differentiation. The constituent cells have a diploid DNA content. Unique cytogenetic aberrations have been anecdotally identified. PFT behaves in a locally aggressive fashion and regional nodal disease can occur despite adequate excision. In rare instances, metastasis to the lungs has been described. No association between specific clinicopathologic features and outcome has been identified. In summary, PFT is a rare but distinct low‐grade myofibroblastic tumor of children and young adults with a misleading clinical and histological appearance.