PMC6769199_01
Case 1: chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Some areas of this biopsy show a proliferation of monotonous small cells compatible with CLL/SLL (A, H&E, 200x). The small B cells are positive for PAX5 (B, 200x), CD5 (C, 200x), and CD23 (D, 200x). H&E indicates hematoxylin and eosin.
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Microscopic images are shown in Figures 1 and 2. PAX5 highlighted numerous small B-cells with expression of CD5 and CD23 in a subset, consistent with a background of CLL/small lymphocytic lymphoma (SLL) (Figure 1).
Case 1: atypical large cells arising in a background of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). The large cells (A, H&E, 400x) are positive for CD163 (B, 400x), CD4 (C, 400x), and PU.1 (D, 400x), consistent with histiocytic differentiation. The large cells are negative for CD45 (E, 400x), PAX5 (F, 400x), CD15 (G, 400x), CD30 (H, 400x), CD5 (I, 400x), and CD23 (J, 400x). H&E indicates hematoxylin and eosin.
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Microscopic images are shown in Figures 1 and 2. CD15, CD30, PAX5, and CD45 (Figure 2). CD15 highlighted background granulocytes, and CD30 highlighted rare immunoblasts. The large atypical cells were positive for CD68 (KP-1), CD163, S100, PU.1, CD4, CD14 (subset), and lysozyme, and negative for CD1a (Figure 2).
Case 1: clonally related chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and histiocytic sarcoma. Fluorescence in situ hybridization confirms homozygous deletion of 13q14 in the large cells of histiocytic sarcoma (left) and the small cells of CLL/SLL (right). The probes shown here are D13S319 [13q14] (red) and LAMP1 [13q34] (green). Homozygous deletion is represented by 0 red signal and 2 green signals, and heterozygous deletion by 1 red signal and 2 green signals.
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Fluorescence in situ hybridization studies were performed at Mayo Clinic College of Medicine (Figure 3) on formalin-fixed, paraffin-embedded tissue.
PMC6769199_02
Case 2: chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and histiocytic sarcoma. This case showed CLL/SLL (A and B, H&E, 200x) in association with histiocytic sarcoma (B, H&E, 200x and D, H&E, 400x). A PU.1 immunohistochemical stain (C, 400x) demonstrated more intense expression in the histiocytic sarcoma than in the CLL/SLL. The CLL/SLL cells were positive for CD20 (E, 200x), CD5 (F, 200x), and CD23 (G, 200x). The histiocytic sarcoma cells were positive for CD163 (H, 400x). H&E indicates hematoxylin and eosin.
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This case is illustrated in Figure 4.
PMC6769199_03
Case 3: low-grade follicular lymphoma and Langerhans cell sarcoma. This case shows a low-grade follicular lymphoma (A, H&E, 200x and B, H&E, 100x) in association with Langerhans cell sarcoma (B, H&E, 100x and D, H&E, 400x). A PU.1 immunohistochemical stain (C, 400x) demonstrates more intense expression in the Langerhans cell sarcoma than in the follicular lymphoma. The low-grade B-cell lymphoma was positive for CD20 (E, 200x) and BCL6 (F, 200x). H&E indicates hematoxylin and eosin.
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This case is illustrated in Figure 5.