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Optical genome mapping (OGM) is a new DNA-based technology which provides comprehensive examination of the entire genome. We report two patients who presented with splenomegaly and leukocytosis with lymphocytosis including villous lymphocytes. Neither patient had lymphadenopathy. Bone marrow evaluation showed involvement by small B-cell lymphoma in a sinusoidal and interstitial distribution, and immunophenotypic analysis showed that the neoplastic cells were positive for B-cell markers and cyclin D1 but were negative for SOX11 and CD5. Initially, the clinicopathologic features in both patients were thought to be suspicious for hairy cell leukemia variant or splenic marginal zone lymphoma. However, OGM detected CCND1 rearrangement: t(2;11)/IGK::CCND1 in one case and t(11;14)/IGH::CCND1 in the other case. These cases illustrate the valuable role OGM can play in establishing the diagnosis of MCL. Case 1 also contributes to the paucity of literature on the rare occurrence of IGK::CCND1 in MCL.

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Herein, we describe the clinicopathologic and genetic characteristics of the first report of simultaneous bone marrow involvement by classical hairy cell leukemia (HCL) and leukemic non-nodal variant of mantle cell lymphoma (L-NN-MCL) with t(11;14)(q13;q32) with BRAF mutation and deletion of TP53. A 40-year-old asymptomatic man was investigated for incidental neutropenia and thrombocytopenia. Flow cytometry showed two distinct monotypic B-cell populations: one expressed CD19 (bright), CD20 (bright), FMC7, CD103, CD25, CD11c, CD123, and IgD (bright) and showed kappa light chain restriction (bright), consistent with HCL and the other kappa-restricted CD5/CD10-negative B-cell population with distinctive immunophenotypic features. The bone marrow biopsy is infiltrated by an abnormal B-lymphoid infiltrate with different patterns of infiltration in different marrow areas. Fluorescence in situ hybridization (FISH) analysis revealed a CCND1/IGH rearrangement, t(11;14)(q13;q32), and deletion of TP53. The BRAF V600E missense mutation was detected by quantitative real-time polymerase chain reaction (PCR). The diagnosis of a composite B-cell neoplasm was composed of HCL together with a second CD5/CD10-negative monotypic B-cell population, with CCND1/IGH fusion, favoring the 2016 WHO new category of L-NN-MCL (CD5/SOX11-negative). Treatment with cladribine and rituximab normalized the blood counts within 6 weeks without significant side effects. L-NN-MCL is one of the smoldering MCL subtypes, recently listed in WHO 2016 as a separate variant, with a particular set of unique features and a less aggressive clinical course compared to classical MCL. To date, the clinicopathological features (including the bone marrow findings) of L-NN-MCL have not been sufficiently characterized in the literature. We describe the first report of synchronous presentation of HCL and L-NN-MCL. This case represents a real challenge from the biologic, diagnostic and therapeutic point of views, due to extremely rare combination of two distinct uncommon B-cell neoplasms. The study of composite lymphomas offers the opportunity to evaluate the etiology and the clonal interrelationship involved in the pathogenesis/evolution of lymphomas.

RESUMEN

In situ mantle cell neoplasia (isMCN) and leukemic non-nodal mantle cell lymphoma (nnMCL) are classified as an indolent subtype of mantle cell lymphoma (MCL). The tumor cells of isMCN are restricted to the inner layer of the lymphoid tissue mantle zone, exhibiting an in situ pattern histologically. On the other hand, nnMCL is distributed in the peripheral blood, bone marrow and sometimes the spleen, but lymphadenopathy or systemic organ involvement is rare. We report a case of isMCN in a submandibular lymph node resected from a 65-year-old Japanese male. The tumor cells were positive for cyclin D1 (CCND1) and SOX11 expression, and were restricted to the mantle zone area of the lymph node. However, tumor cells were also detected in the stomach mucosa, bone marrow tissue and peripheral blood, suggesting nnMCL. isMCN and nnMCL may have a partly overlapping disease spectrum, although the correlation between these two subtypes has not been well described. This present case demonstrated characteristics overlapping between isMCN and nnMCL.

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Mantle cell lymphoma (MCL) is usually CD23 negative, a feature helpful in distinguishing MCL from chronic lymphocytic leukemia/small lymphocytic lymphoma. However, a subset of MCL cases can be CD23+. Limited data are available regarding the clinicopathological features and prognosis of patients with CD23+ MCL. In this study, we reviewed 798 cases of MCL and identified 103 (13%) that were CD23+ by flow cytometry, all of which were positive for cyclin D1 and/or associated with CCND1/IGH. In all cases of CD23+ MCL, CD23 expression was dim partial or dim, unlike moderate to bright CD23 expression observed in chronic lymphocytic leukemia/small lymphocytic lymphoma. The clinicopathological features and outcome of patients with CD23+ MCL were compared with 240 patients with typical MCL negative for CD23. Patients with CD23+ MCL more often had an elevated leukocyte count (33% versus 18%, P = .009), bone marrow involvement (89% versus 78%, P = .02), stage 4 disease (87% versus 77%, P = .03), and a leukemic presentation (42% versus 11%, P = .0001). CD23+ MCL was also more often positive for CD200 (17% versus. 4.6%, P = .0005) and less commonly positive for SOX11 (55% versus. 74%, P = .027). All other clinicopathological features were similar. With similar treatment regimens and observation times, patients with CD23+ MCL had a significant better overall survival (P = .02) and progression-free survival (P = .029). In conclusion, CD23 expression was observed in 13% of MCL cases and is associated with a better prognosis in patients with MCL. CD23 is associated with leukocytosis, a leukemic presentation, bone marrow involvement, CD200 expression, and a lower frequency of SOX11 positivity.

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