Epithelioid sarcoma with unusual radiological findings.

The case of a patient with epithelioid sarcoma in the right arm is reported. The diagnosis was delayed because of misinterpretation arising from complexity in the MR findings, including a honeycomb pattern in the subcutaneous fat simulating lymphedema, and an intramuscular diffuse high signal intensity on T2-weighted images without a discrete mass lesion. The histological findings revealed that the diffuse muscular abnormality mainly resulted from denervation of the muscles due to perineural invasion by the tumor, and subcutaneous edema from lymphedema secondary to lymphatic tumor spread concurrent with lymphatic fibrosis. Multiple foci of cortical erosions in the humerus, a rare manifestation of this tumor, were detected 6 months later.