Uncommon location, diagnostic challenge: A case series of acral low-grade fibromyxoid sarcoma.

Low-grade fibromyxoid sarcoma (LGFMS) arising at acral sites is exceedingly rare, and its clinicopathologic features and clinical outcomes remain poorly characterized. Herein, we report a cohort of ten cases of acral LGFMS. The cohort included six males and four females, with a mean age at diagnosis of 23 years (median, 14 years; range, 2-67 years). Tumors arose in the foot (n = 7) or hand (n = 3). All cases were superficially located and exhibited classic morphologic features of LGFMS. Diffuse MUC4 expression was observed in all nine cases tested. Fluorescence in situ hybridization (FISH) and next-generation sequencing (NGS) demonstrated FUS gene rearrangements in all five cases analyzed. Clinical follow-up was available for six patients, with a mean duration of 37 months (range, 6-91 months). One patient developed a local recurrence and subsequently underwent digital amputation. No patients have developed metastases to date. Recognition of this rare, deceptively bland neoplasm in acral locations is critical, given its potential for local recurrence and metastatic spread.