Abstract
Chronic expanding hematoma is an uncommon condition that may present as a slowly enlarging soft-tissue mass and closely resemble malignant tumors on imaging. We report the case of a 55-year-old woman with no history of trauma or underlying medical disease who presented with a progressive mass of the left thigh. Imaging studies demonstrated a heterogeneous soft-tissue lesion raising suspicion for a soft-tissue sarcoma. As imaging findings were inconclusive, the patient underwent surgical excision for diagnostic confirmation. Histopathological analysis revealed a chronic expanding hematoma with no evidence of malignancy. This case emphasizes the importance of considering chronic expanding hematoma in the differential diagnosis of slowly growing extremity masses, even in the absence of predisposing factors, to avoid misdiagnosis and inappropriate management.