Myofibroblastic sarcomas: a clinicopathologic analysis of 15 cases and review of literature

To analyze the clinicopathological, immunohistochemical, and histochemical characteristics of myofibroblastic sarcoma arising in different locations to improve the knowledge of this disease. Retrospective study of 15 myofibroblastic sarcoma cases and literature review. The patients included seven males and eight females (age, 6-73 years; mean, 46.6 years). A painless mass was the main clinical symptom. Histologically, the tumor cells were mostly solitary with non-clear cell boundaries; fusiform, oval cells with eosinophilic cytoplasm arranged in a fasciculate, woven pattern were observed. Fat spindle cells, spindle cells, or fine wavy nuclei with pale staining and small eosinophilic nucleoli were noted. Immunohistochemically, most cells were positive for vimentin, calponin, fibronectin, and smooth muscle actin; few cells showed positive desmin staining; and all were negative for h-caldesmon. Van Gieson and Masson stains showed mixed yellow/red and red/blue staining, respectively. During the clinical follow-up of 14 patients, five and one experienced local recurrence and distant metastasis, respectively, one died, while the other seven were alive with no evidence of disease. Myofibroblastic sarcoma is a rare mesenchymal malignant tumor prone to relapse. It resembles fibrosarcoma, malignant fibrous histiocytoma, and leiomyosarcoma in morphology and is easy to misdiagnose. Correct diagnosis requires morphological, histochemical, and immunohistochemical analyses.