Pseudomyogenic hemangioendothelioma secondary to fibrous dysplasia of the left lower extremity in a 14-year-old female: a case report

BACKGROUND Pseudomyogenic hemangioendothelioma is a rare soft tissue tumor usually found in young adults, predominantly males. Fibrous dysplasia is a common benign bone tumor, which accounts for 5~7 % of all the primary benign bone tumors. However, pseudomyogenic hemangioendothelioma secondary to fibrous dysplasia is extremely rare. To the best of our knowledge, this is the first case of pseudomyogenic hemangioendothelioma secondary to fibrous dysplasia. CASE PRESENTATION This study describes a case of a 14-year-old female who suffered from pseudomyogenic hemangioendothelioma secondary to fibrous dysplasia of the left lower extremity. The patient underwent two operations successively due to pathological fractures in the left femur and tibia in a local hospital. She was diagnosed with fibrous dysplasia according to the postoperative pathological examinations. However, less than 1 year later, she was diagnosed with a recurrence of fibrous dysplasia in her left femur during a follow-up in our hospital. She underwent a curettage and grafting in the left femur. Postoperative pathological examinations demonstrated the diagnosis of fibrous dysplasia. Nevertheless, she presented to our clinic with a chief complaint of pain and swelling in her left tibia and calcaneus 4 months later. The patient underwent fine-needle aspiration in her left tibia. According to the histological and immunohistochemical findings, the diagnosis of pseudomyogenic hemangioendothelioma was confirmed by an expert pathology consultant. Finally, the patient had to undergo an amputation of the left thigh. Postoperative pathological examinations confirmed the diagnosis of pseudomyogenic hemangioendothelioma. Postoperative follow-up at 3 months disclosed no evidence of recurrent disease and no residual side effects from therapy. CONCLUSIONS Pseudomyogenic hemangioendothelioma is a rare endothelial neoplasm which often mimics myoid and epithelioid tumors morphologically. For the diagnosis, the immunostaining is very important but not decisive and enough. Analysis based on any single factor or incomplete information may easily lead to arbitrary conclusion. Clinical information including age, gender, tumor location, disease course, and recurrence is important for appropriate diagnosis, and full understanding of the tumor is indispensable.