Pseudomyogenic Hemangioendothelioma of the Talocalcaneal Coalition: A Case Report

Pseudomyogenic hemangioendothelioma is a rare soft tissue tumor most often found in the lower extremities and predominantly occurring in males. The talocalcaneal coalition is an anatomic anomaly that develops between the talus and calcaneus bones, can cause hindfoot pain and subtalar joint stiffness, and has a prevalence of less than 1%. We present what is to our knowledge the first case report of a 17-year-old male with pseudomyogenic hemangioendothelioma occurring within a talocalcaneal coalition. The patient was treated with local excision of the tumor and the coalition. His American Orthopaedic Foot & Ankle Society ankle/hindfoot score went from 70 preoperatively to 92 at 1 year postoperatively, and he has had no evidence of recurrence at 1 and 3 years postoperatively. These tumors have suggestive but not diagnostic computed tomography, magnetic resonance imaging, and histopathological findings, and they are associated with a uniquely characteristic immunophenotype, including immunochemical reactivity to CD31, FLi-1, INI-1, ERG, and FOSB. Primary treatment of pseudomyogenic hemangioendothelioma most often involves local excision (but can require amputation) and may include adjuvant radiotherapy and/or chemotherapy. It has a relatively favorable prognosis, with a moderate risk of local recurrence and a low risk of metastases. Because metastases have been reported many years after treatment, long-term follow-up is necessary. (c) 2021 by the American College of Foot and Ankle Surgeons. All rights reserved.