PMC8404676_01
(a) Multiple, dusky reddish, irregular shaped nodules with fine scales bilaterally distributed over the trunk. (b) Close-up view shows an oval-shaped nodule with fine scales. (c, d) After 9 months of treatment, the lesions became smaller and flatter.
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A 53-year-old man presented with asymptomatic, multiple, dusky reddish nodules on his trunk, which had persisted for 7 years (Figure 1(a) and (b)).
(a) Multiple, nodular infiltrates involving the reticular dermis, sparing the overlying epidermis (H&E, x40). (b) Tumor cells, small to medium sized and having irregular nuclei, are present on the left of the field and plasma cells are seen in the center (H&E, x400). (c) Scattered mast cells (arrowheads) and eosinophils (arrow) are found at the periphery of the infiltrate (H&E, x400). (d, e) Mast cells are stained with toluidine blue and CD117 (toluidine blue, CD117, x400). (f, g) Immunohistochemistry studies revealed multiple plasma cells (MUM1, CD138, x40). Compared with the (h) lambda light chain, (i) kappa light chain is strongly expressed (x40).
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Histological findings of the biopsy specimen showed nodular to diffuse dermal infiltration of lymphocytes with irregular nuclei, eosinophils, plasma cells, and mast cells (Figure 2(a)-(c)). Kappa light chain restriction was suggested in the immunostaining results of the immunoglobulin (Ig) light chain (Figure 2(h) and (i)). Toluidine blue (Figure 2(d)) and CD117 (Figure 2(e)) staining showed positivity, and several mast cells were confirmed. MUM1 and CD138 (Figure 2(f) and (g)) showed diffuse positivity and confirmed positive reaction in plasma cells.
(a) Nodular infiltrates in the dermis (H&E, x40). (b) Patchy positivity is shown (CD20, x100). (c) Focal positive cells in the center of the follicle (BCL-6, x100). (d) Numerous BCL-2 positive cells are present except in the small germinal center areas (BCL-2, x100).
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CD20 staining, a B-cell marker, revealed reactive lymphoid follicles with patch positivity (Figure 3(b)). Periphery of lymphoid follicles showed BCL-2 positivity (Figure 3(d)) and BCL-6 positivity focally at the center (Figure 3(c)).