Intrathoracic Extramedullary Haematopoiesis Manifested as a Neoplastic Lesion Within Anterior Mediastinum

Intrathoracic extramedullary hematopoiesis (EMH), the formation of apparently normal blood cells outside the confines of the bone marrow, is an uncommon but well-defined entity. It is usually associated with hematologic disorders and located in the lower paravertebral sulci or rarely in the pleura. We report a case of EMH, which presented in a patient without hematologic disorders and was manifested as an anterior mediastinal mass. The first interesting aspect of our case was that EMH occurred in a patient with normal laboratory findings and no past medical history of anemia. The second remarkable characteristic was that EMH manifested as an anterior mediastinal mass, mimicking a neoplastic lesion. Definitive diagnosis of EMH was established by a video-assisted thoracoscopic surgical biopsy. In light of this diagnosis, no further surgical procedure was carried out. (Ann Thorac Surg 2009;88:2001-4) (C) 2009 by The Society of Thoracic Surgeons