ABSTRACT
INTRODUCTION: Extramedullary hematopoiesis is a complication of myeloproliferative neoplasms or of chronic hemolysis. The more frequent localizations are splenic, ganglionic or paraspinal. Rarely, extramedullary hematopoiesis is associated with solid cancer. CASE REPORT: We report an original case of sarcoma located in an extramedullary hematopoiesis mass in a 72-year-old woman suffering from hereditary spherocytosis. An asymptomatic right paravertebral mass was found in 2004; the biopsy confirmed extramedullary hematopoiesis. In 2016, the patient was hospitalized due to paravertebral pain. Computed tomography showed the extension of the right paraspinal mass to pleura and mediastinum as well as vertebral bone lysis. Positron emission tomography showed an intense hypermetabolism. The biopsy showed undifferentiated sarcoma. CONCLUSION: This case report illustrates the risk of neoplastic transformation of extramedullary hematopoiesis, and the need for a biopsy when confronted to atypical aspect.