Figure 2. Subsequent bone marrow biopsy shows subtle involvement by the same lymphoid neoplasm, consisting of atypical lymphocytes of varying sizes with pale to clear cytoplasm, with small interstitial lymphoid aggregates and hypercellularity for the patient’s age (A: H&E stain, 100X magnification). The tumor cells are highlighted by positive CD4 (B) and CD56 (D) stain. A positive EBER in-situ hybridization further confirmed the subtle bone marrow involvement by natural killer-T-cell lymphoma (C: 3,3’-DAB chromogen stain). Of note, testing of the bone marrow sample was performed at New York-Presbyterian Weill-Cornell Medical Center utilizing magenta-red chromogenic staining. H&E – hematoxylin and eosin; DAB – diaminobenzidine; EBER – EBV-encoded small RNA.