Objective: Acute and lymphoma type adult T-cell leukaemia/lymphoma (ATLL) patients show an aggressive clinical course. While some clinical signs indicate good prognosis, definitive cytohistological prognostic factors have yet to be described. Methods:We classified 65 ATLL patients into three groups by tumour cell size and nuclear pleomorphism on fine-needle aspiration and tumour touch smear samples.Semi-quantitative analysis of background small lymphocytes, reactive CD20-positive B cells and CD8-positive T cells was performed.Results: Thirty-one patients had pleomorphic lymphoma with predominantly medium-sized cells and coarse granular nuclei. Another 24 patients showed pleomorphic large cell lymphoma with stippled chromatin. The remaining 10 demonstrated monomorphic large lymphoma cells with fine granular chromatin. Patients with pleomorphic lymphoma with medium-sized cells showed significantly higher serum lactate dehydrogenase and lower CD30 and C-MYC expression in lymphoma cells than the other two groups (P = .0216, P < 0.01, respectively). Patients with pleomorphic medium-sized ATLL had few usual small lymphocytes observed on routine morphological examination and showed less concurrent detection of CD20-positive B cells and CD8-positive T cells, both of which were lower than in the other two groups (P = .006, P = .019, respectively). Furthermore, ATLL patients with predominantly medium-sized lymphocytes exhibited a worse prognosis than patients with pleomorphic large cells (P = .0197). Background small lymphocytes and concurrent detection of CD20-positive B cells and CD8-positive T cells may thus be good prognostic factors (P = .011, P = .021, respectively). Conclusions:Morphological features, size of neoplastic cells and background nonneoplastic lymphocyte (B cells and CD8-positive T cells) volume appear to influence the prognosis of patients with aggressive-type ATLL. K E Y W O R D Sadult T-cell leukaemia/lymphoma, cytology, prognosis, tumour-infiltrating lymphocytes | 403 KOBATA eT Al.

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