Soft Tissue Tumors: Low grade fibromyxoid sarcoma

Clinics and pathology Disease Low grade fibromyxoid sarcoma (LGFMS) Embryonic origin Cellular origin unknown, but presumably of mesodermal derivation. Tumor cells show fibroblastic differentiation. Etiology Unknown. No known risk factors. Epidemiology Low grade fibromyxoid sarcoma is supposed to be rare, but as it is difficult to diagnose the true incidence is unknown. Patients of any age may be affected, and the male: female ratio is 1:1. Clinics Low grade fibromyxoid sarcoma usually presents as a painless mass, typically in the proximal extremities. Pathology Classical cases of LGFMS display a mixture of hypocellular, collagen-rich areas and more cellular, myxoid areas. A characteristic feature is the whorling growth pattern, often seen at the transition from hypocellular to more cellular, myxoid areas. Mitotic figures are rare. A subset of LGFMS shows focal collagen rosettes. Treatment The only consensus treatment for low grade fibromyxoid sarcoma is surgical excision. Prognosis When radically excised, the prognosis is usually good. However, local recurrences have been reported in approximately 10% of the cases, and distant spreading occurs in 5-10% of the cases.