Immunostaining for cyclin D1 is essential for reliable diagnosis of mantle cell lymphoma (MCL). However, a small number of cyclin D1-positive lymphomas other than MCL have been encountered. Our goal was to investigate the morphological spectrum of MCL as a disease entity, based on cyclin D1 overexpression. We reviewed 181 biopsy specimens obtained from 168 cases of cyclin D1-positive MCL. Typical findings were the presence of nodular (53.9% of cases) or diffuse (46.1%) histological patterns, containing mantle zone patterns (16.8%), naked germinal centers (33.5%) and perivascular hyaline deposition (83.2%). Unusual findings of residual germinal centers with a mantle cuff (four cases) and follicular colonization (two cases) were seen. High magnification showed a monotonous proliferation of tumor cells with cytological diversity including small (3.0%), intermediate (43.1%), medium (34.1%), medium-large (13.2%) and large (6.6%) cells. Pleomorphic and blastic/blastoid variants were encountered in 9.6 and 7.2% of cases, respectively. Three cases had foci of cells of considerable size, with a moderately abundant pale cytoplasm resembling marginal zone B cells. Two cases showed an admixture of cells which appeared transformed and mimicked the histology of chronic lymphocytic leukemia/small lymphocytic leukemia. In one, neoplastic mantle zones were surrounded by sheets of mature plasma cells, resembling the plasma cell type of Castleman's disease. An admixture of areas characteristic of MCL and of other larger cells, indicating histological progression or a composite lymphoma, were observed in seven cases. In high-grade lesions of five cases, nuclear staining of cyclin D1 was rarely detected. In our experience, cyclin D1 expression was also found in nine lymphomas other than MCL (five plasma cell myelomas, three Hodgkin's disease and one anaplastic large cell lymphoma). The application of cyclin D1 staining prompted us to recognize the broad morphological spectrum of MCL. MCL can be diagnosed with the application of cyclin D1 immunostaining, if careful attention is given to architectural and cytological features.

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We describe a case of Hodgkin lymphoma developing in a 9-year-old girl with polyarticular, rheumatoid factor-positive juvenile idiopathic arthritis treated with methotrexate (MTX), prednisone, and naproxen for 5 years. Pathologic and molecular analyses revealed that the Hodgkin cells contained Epstein-Barr virus and the viral DNA was monoclonal. She achieved complete remission after MTX withdrawal, chemotherapy, and radiation. To the best of my knowledge, this is the sixth report of Hodgkin lymphoma in patients with juvenile idiopathic arthritis receiving low dose MTX therapy.

A 10-year-old patient with nasopharyngeal carcinoma (NPC) was studied for mutations within the carboxy-terminal portion of the Epstein-Barr virus (EBV) latent membrane protein (LMP)-1 gene. The EBV genome, defined as type A, was detected in biopsied tumor specimens by Southern hybridization with specific probes. Sequence analysis of the carboxy-terminal part of the LMP-1 gene revealed no deletions but seven single-base substitutions, four of which were found to be identical to those previously detected in codons for amino acids 322 to 366 in the Chinese NPC CAO. Although yet unresolved, the observed mutations may be associated with the pathogenesis of NPC.

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