Myeloblasts in Pleural Effusion

A 68-year-old woman presented with loss of strength in lower limbs. Magnetic resonance imaging revealed a neoplasic infiltration at dorsal level. A biopsy specimen showed myeloid sarcoma. A complete blood count showed hemoglobin of 10.9 g/dL, platelets 113 × 109/L and white blood cell count 3.05 × 109/L. A peripheral blood smear and a bone marrow examination revealed no alterations. The patient also had a pleural effusion. The pleural fluid analysis revealed a white blood cell count of 3882/uL and microscopic examination revealed that 53% of cells were myeloblasts (Figure 1). The immunophenotypic study was compatible with myeloid sarcoma, agreeing with the immunohistochemical profile of the bone tumor. Myeloid sarcoma is a tumor mass of myeloblasts ocurring in an extramedullary site. It is an infrequent neoplasm that usually occurs in the context of acute myeloid leukemia, presentation as a primary lesion without underlying hematological disorders is excepcional.