Low-grade fibromyxoid sarcoma - Clinicopathologic case report with review of the literature

Low-grade fibromyxoid sarcoma is a rare, benign-appearing soft tissue neopl asm with an aggressive clinical course characterized by multiple local recu rrences over several years, with ultimate spread to lung and occasionally t o bone. Thus far, a total of 24 cases of low-grade fibromyxoid sarcoma have been reported in the literature. The authors present an additional case th at grossly and microscopically emphasizes a pronounced lobular pattern of c ontrasting areas of cellularity showing high proliferative activity, as dem onstrated by a proliferation marker, Ki 67 with MIB-1, and hypocellular are as with prominent myxoid component and abundant collagen fibrils. There was predominance of delicate capillary-sized stromal vessels with collagenized walls in both cellular and myxoid areas. The unusual features in this case were osseous metaplasia, prominent intranuclear pseudoinclusions, DNA tetr aploidy, and membrane-bound intracytoplasmic fat vacuoles. The immuno-profi le and cytologic and ultrastructural features are described, After the exci sion of the tumor, the patient was treated with radiotherapy without chemot herapy. The patient has been observed for 26 months and is alive without th e evidence of disease. The postoperative follow-up with axial computed tomo graphy at 24 months showed no evidence of disease, except postsurgical fibr otic changes.