Serviço de Hematologia e Hemoterapia do HC-FM-USP, São Paulo. Correspondência: Renata Bizzetto Rua Matias Aires nº 300, 9440-9935 E-mail: rbizzetto@hotmail.com Revisão / ReviewIntrodução O LPSNC é um linfoma extralinfonodal raro que, por definição, ao diagnóstico, encontra-se restrito ao parênquima cerebral, à meninge e/ou medula espinhal e/ou olhos.1 Após ter sua incidência triplicada nas últimas três décadas, atingiu taxas atuais de 0,4/100.000 habitantes.2 Anteriormente respondia por 0,5% a 1,5% de todas as neoplasias do SNC, representando atualmente 4% a 7% destes tumores.3 O aumento da incidência ocorreu em indivíduos imunossuprimidos 4 e em imunocompetentes. 1Os casos de LPSNC não relacionados à SIDA acometem pacientes de 45 a 70 anos, com predomínio acima de 60 anos. Raramente ocorrem em crianças. 4,5,6 Há discreto predo-

A patient with myasthenia gravis and a thymoma did not respond to thymectomy. He was submitted to radiotherapy concurrent with steroid therapy followed by an alkylating based chemotherapy. Four years later, he developed an otherwise typical Philadelphia chromosome/BCR-ABL positive chronic myelogenous leukemia (CML) that quickly evolved to a blast crisis. We discuss the possible cause-effect mechanism between the previous treatment and CML, and suggest that a distinct mechanism, albeit unknown, could be involved in the development and progression of secondary CML.

Although the small B-cell lymphomas show major morphologic overlapping, they have been recently shown to be distinct entities with several biologic and clinical differences. Therefore, the utility of a panel of paraffin-reactive antibodies in differentiating these neoplasms was investigated. Using clinical data and morphologic criteria, 134 cases of small B-cell lymphomas were grouped as those with (1) one strongly suggested diagnosis, (2) differential diagnosis between two types of lymphomas, and (3) small B-cell lymphoma without hints for further subclassification. With a panel of antibodies including CD5, CD10, CD23, CD43, bcl-2, and cyclin D1, most but not all cases could be precisely categorized. This panel confirmed the diagnosis in 96.5% of the cases from group 1. In group 2 it confirmed one of the two diagnoses in 81.5% of the cases. In group 3 it established a definitive diagnosis in 55% of the cases. When all groups were considered, a correct diagnosis could be established for 88.1% of cases; for 6.7% of them the authors remained with two possible diagnosis, and the broad "small B-cell lymphoma" was the only diagnosis for 5.2% of cases. CD10 separated most follicular lymphomas from other small B-cell lymphoid neoplasms. CD23 separated small lymphocytic lymphoma/chronic lymphocytic leukemia. Cyclin D1 separated mantle cell lymphoma. The present study selected CD10, CD23, and cyclin D1 as a minimal panel for the classification of small B-cell lymphomas, yielding a final diagnosis in 88.1% of the cases.

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