PMC3583111_01
Histological features of lymph node. (A and B) Right posterior cervical lymph node, (A) H&E, 2x. The node is nearly completely effaced with minimal residual follicles. (B) H&E, 20x. Sheets of monocytoid cells in marginal zone. (C-F) Right cervical neck mass. (C) H&E, 60x. Sheets of monocytoid cells similar to those seen in the cervical lymph node. (D) H&E, 60x. Area of larger cells with focal necrosis. (E) H&E, 40x. Monocytoid cells and groups of larger cells (circle) with hyperchromasia. (F) MIB1 immunostain, 20x. Transformation areas with large cells show MIB-1 labeling index as high as 70%.
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Microscopic examination showed almost complete effacement of the node (Figure 1(A)). Follicles were replaced by atypical monocytoid cells (Figures 1(B) and 1(C)), which stained positive for PAX-5, CD19, and CD20, but were negative for CD5 and cyclin D1. These morphologic and immunohistochemical (IHC) findings are characteristic of a nodal MZL.The tissue from the deep neck mass revealed similar histology but an area with larger, more hyperchromatic cells (Figures 1(D) and 1(E)) and a higher mitotic rate, with a MIB-1 labeling index of up to 70% (Figure 1(F)).
Chest skin lesion. (A) Clinical photo of violaceous skin lesion on the patient's chest. (B) Punch biopsy, H&E, 2x. MZL cells invading the dermis. (C) Punch biopsy, H&E, 40x. Small lymphoid cells consistent with MZL are observed here, but also the larger, more hyperchromatic cell population with many mitotic figures, similar to findings in the transformation areas of neck mass.
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Punch biopsy of one of the skin nodules (Figure 2(A)) showed diffuse involvement of the dermis (Figure 2(B)). The histology showed mostly small monocytoid B cells (Figure 2(C)), again with a classic MZL immunophenotype: BCL6 and CD23 positive in remnant follicles replaced by atypical CD20 positive monocytoid B cells.
FISH and cytogenetics analysis. (A) FISH performed on a touch preparation of representative lymph node tissue shows only one positively tagged 20q12 (red signal) per cell. Control tag 6p11 (green) shows dual positivity. FISH is diagnostic for del(20q12). (FISH probes from Abbott Molecular, Inc.) (B) Karyotype of bone marrow aspirate. Cytogenetics performed on bone marrow tissue reveals deletion of 20q11.2 (arrow).
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fig3
FISH on representative lymph node tissue revealed del(20q), near 20q12 (Figure 3(A)). However, a karyotype of the bone marrow aspirate also revealed a del(20q), near 20q11.2 (Figure 3(B)).