Bone marrow aspiration, biopsy, and immunohistochemical stain results of the patient. The bone marrow aspiration (A–C) showed hypocellular marrow due to dilution by peripheral blood with increased infiltration of small to medium-sized neoplastic cells, which showed deeply stained nuclei, finely dispersed nuclear chromatin without distinct nucleoli, scanty amount of cytoplasm, and frequent nuclear moulding defined as conformity of adjacent cell nuclei to one another (Wright stain, ×400). The bone marrow biopsy (D–F) showed hypercellular marrow with proliferation of neoplastic cells in a diffuse and patched pattern accompanied by frequent nuclear moulding (Hematoxylin and Eosin stains, ×200 in D, ×200 in E, ×400 in F). Subsequently performed immunohistochemical stains showed the presence of neoplastic cells with positivity for CD56 (G, ×400), cytokeratin (H, ×400), and chromogranin (I, ×400).