TY - JOUR AU - Carvalho, Rita AU - Mafra, Manuela PY - 2016 TI - How do I diagnose Extramedullary Hematopoiesis JF - Diagnostic Pathology; Vol 2 No 1 (2016): 2016 DO - 10.17629/www.diagnosticpathology.eu-2016-2:107 KW - Extramedullary hematopoiesis; Extramedullary myeloid sarcoma; : Posterior mediastinum, para-vertebral mass; CD34, CD117, TdT N2 - Extramedullary hematopoiesis occurs in bone marrow disorders and is most commonly seen in thalassemia and myelofibrosis. We present a case of a 58 year-old male, with a history of thalassemia, which presented with a para-vertebral mass composed of hematopoietic tissue. When considering the differential diagnosis, a primary concern was an extramedullary proliferation of neoplastic hematopoietic elements, like extramedullary myeloid sarcoma. Neoplastic extramedullary proliferations can consist of triline age marrow elements and closely mimic the appearance of benign extramedullary hematopoiesis. The morphologic appearance may be a diagnostic clue, but cannot be completely relied upon. UR - https://www.diagnosticpathology.eu/content/index.php/dpath/article/view/107