[CD8+ agranular lymphocyte proliferative disorder with T-cell receptor beta-chain gene rearrangement associated with thymoma and neutropenia].

A 58-year-old male with a 10-years history of thymoma was admitted to our hospital because of the respiratory infection. Hepatosplenomegaly and systemic lymphadenopathy were revealed on physical examination. Chest roentgenogram showed a large anterior mediastinal tumor and a right pleural effusion. Blood examination showed Hb 11.5 g/dl, leucocyte count 1,600/microliters (1% neutrophils, 34% monocytes, 65% lymphocytes) and platelet count 11.2 x 10(4)/microliters. The lymphocytes in the peripheral blood and pleural fluid were mostly small agranular mature lymphocytes and CD2+ 3+ 4- 8+. A monoclonal rearrangement of TCR beta chain gene was found using Southern blot analysis of the lymphocytes in the peripheral blood and pleural fluid. The CFU-GM colony formation by bone marrow cells was normal, and not suppressed by the patient's serum or peripheral blood lymphocytes. Neutrophil-associated IgG was increased with a direct immunofluorescence test. Serum IgG level was slightly decreased. Radiation therapy for thymoma exerted no effect. Treatment with prednisolone 60 mg daily resulted in complete disappearance of the pleural effusion and partial improvement of hepatosplenomegaly, thymoma and neutropenia. Histological examination of the thymoma revealed predominantly spindle cell type. He is still in good condition 21 months after diagnosis. This case seems to represent neoplastic proliferation of mature CD8+ T cells associated with thymoma.