Fibrosarcoma with deceptive benign presentations: a report of two cases

Low-grade fibromyxoid sarcoma and myxofibrosarcoma are malignant soft tissue tumors, fibrosarcomas, of shared clinical and imaging appearances. We report sarcomatous lesions in soft tissue with deceptively benign clinical and imaging appearances, and correlate findings with those of histologic analysis. Two patients presented with a long history of painless swelling at the dorsum and upper extremity and denied any constitutional symptoms. Sonography and magnetic resonance imaging suggested the presence of benign soft tissue lesions of a predominant fluid-like consistency. Despite indolent clinical and imaging characteristics, in both cases, histopathology disclosed a diagnosis of spindle cell-type soft tissue sarcoma, designating an aggressive tumor. Knowledge of the seemingly benign clinical and imaging features of fibrosarcomas is required to raise the possibility of malignancy in soft tissue that may be underdiagnosed or misdiagnosed. The importance of a correct diagnosis and the implications of surgical resection, irradiation, and systemic oncological therapy are quite obvious.