Extramedullary Hematopoiesis at the Posterior Mediastinum in Patient with Hereditary Spherocytosis: A Case Report
A 48-year-old male presented at our clinic with a thoracic mass, which had been incidentally detected on chest computed tomography (CT), and was not clear on routine chest radiography (). Chest CT revealed a 3.2-cm flat posterior mediastinal mass at the T8 level (), which led to suspicions of a neurogenic tumor, such as ganglioneuroma or neurilemmoma. However, magnetic resonance images showed slightly lower signal intensity in the bone marrow of all the thoracic vertebrae and a combined finding of myelofibrosis in the bone marrow, which suggested that the posterior mediastinal mass could have been extramedullary hematopoiesis (EMH). A technetium-99m phytate bone marrow scan was performed and asymmetric increased uptake was noted at the 8th thoracic vertebra (). The patient had a history of hereditary spherocytosis, and had undergone splenectomy, cholecystectomy, and distal pancreatectomy 4 years previously. His laboratory findings were as follows: white blood cells 6.06×103/µL, hemoglobin 14.7 g/dL, platelets 171,000/µL, segmental neutrophils 27%, lymphocytes 51.7%, monocytes 15%, and eosinophils 4.6%. Chemistry analysis findings were within the normal range. Although the patient had no specific symptoms and the possible diagnosis was EMH, we decided to confirm the pathologic diagnosis to differentiate the mass from neurogenic tumors and other posterior mediastinal diseases, and to remove the potential risk of spinal cord compression because the lesion was located close to the neural foramen.\nVideo thoracoscopic surgery was performed and a 2-cm dark-blue pleural mass was found () and excised completely without difficulty. A frozen section examination showed that the mass was consistent with EMH. A permanent histopathologic examination revealed myeloid tissues composed of hematopoietic cells and confirmed a diagnosis of EMH (). The patient's postoperative course was uneventful and he was discharged without complications on the 5th postoperative day.