Increased CD38 expression in MTCN. (A) These results represent a retrospective analysis of data acquired from fresh specimens from multiple biopsy sites (bone marrow, lymph nodes, spinal fluid, peripheral blood, pleural fluid, tonsils, soft tissue, parotid, and small bowel) from 51 patients, 7 healthy controls, and 7 MM controls, which were examined by flow cytometry. The percentage of CD38 from within the phenotypically abnormal malignant population across the MTCN spectrum was also compared with CD38 staining on CD3⁺ cells in peripheral blood of healthy donors and samples from patients with MM. PTCL-NOS (P = .0026) and T-PLL (P = .0202) were statistically significantly increased as analyzed by the Kruskal-Wallis test. (B) The CD38 MFI of the gated neoplastic T-cell population from patients with MTCN compared with that of samples from patients with B-cell neoplasms (P < .0001) and patients with MM (P < .0001) by Mann-Whitney analysis. Each data point represents a unique patient with MTCN.