A Case Report of Chronic Expanding Hematoma Initially Misdiagnosed as a Soft Tissue Sarcoma

The differential diagnosis of a large soft tissue mass is challenging, and is further complicated by the difficulty of differentiating chronic expanding hematoma from a malignant tumor given similar clinical and radiological features. Here, we report the case of a patient with a large thigh mass that was ultimately diagnosed as a chronic expanding hematoma. The mass appeared 3 years before the patient visited our clinic and extended from the left flank to the thigh. Diagnostic modalities including computed tomography, magnetic resonance imaging, ultrasonography, and aspiration as well as incisional biopsy suggested that the mass was a malignant tumor such as a liposarcoma or fibrosarcoma; however, this case could not be definitively preoperatively diagnosed as pathologists required the entire mass for diagnostic confirmation. We initially performed a palliative resection rather than a wide radical excision to obtain the whole specimen even though intraoperative findings such as dense adhesion to adjacent tissues and brown liquid material leaking from the mass also suggested the possibility of a malignancy. The final postoperative pathological diagnosis was a benign chronic hematoma. Key Words: Hematoma; Malignancy; Misdiagnosis; Biopsy.