Huge Ancient Hematoma in the Calf

Ancient hematoma is one of several lesions that require differentiation from soft tissue neoplasm. This hematoma, named as such by Mentzel et al. [1], is a benign soft tissue tumor surrounded by a fibrous pseudocapsule with inflammatory cells present inside the capsule that gradually expands in size. Chronic expanding hematoma, designated by Reid et al. [2], is a hematoma that increases slowly in size over more than a month after onset. Ancient hematoma is also called chronic expanding hematoma in the field of clinical medicine. It can mimic soft tissue sarcoma because of its increasing size after the initial hemorrhage A 44-year-old male complained of a protruding giant mass (10 cm × 15 cm) in his right calf and numbness of his right leg due to compression by the mass (Fig. 1). The patient had no history of medical disease but a history of trauma involving a pedestrian traffic accident 20 years previously. He had a 16-cm vertical postoperative scar in his right calf after a right knee operation conducted at the time of accident. Unfortunately, the nature of the knee operation could not be established since the records of the surgery were no longer available. At the time, the mass had been palpable 2 weeks after the knee surgery, but no treatment had been done. The mass was evaluated from radiologic findings. Contrast computed tomography (CT) revealed a huge lobulated cystic mass at the intermuscular septal and subcutaneous fat layer level. Internal scattered calcification and septation were found; they were suggestive of post-trauma cyst, extra-skeletal chondrosarcoma, and synovial sarcoma. A magnetic resonance imaging (MRI) scan with contrast enhancement suggested post-traumatic giant epidermal inclusion cyst or malignant fibrous histiocytoma (Fig. 2). To rule out malignancy and evaluate pathology, ultrasonography-guided needleaspiration biopsy was done. Soft tissue fragments and reddish aspirates were obtained, which were suggestive of a post-traumatic epidermal cyst or sarcoma. Surgical exploration under general anesthesia revealed a pseudocapsulated mass measuring 11