EBV-Negative Monomorphic B-Cell Posttransplant Lymphoproliferative Disorder with Marked Morphologic Pleomorphism and Pathogenic Mutations in ASXL1, BCOR, CDKN2A, NF1, and TP53

Figure 1

Histological findings of the small bowel tumor. Low power examination (50x) shows (a) nodular cellular areas with scattered large atypical cells surrounded by thick bands of fibrosis as well as (b) monomorphic areas with dense blue cells and more clear areas and foci of necrosis and (c) monomorphic areas with increased eosinophils in the lamina propria. Higher power examination (200x) of the different areas of the specimen reveal a variety of morphologies with (d) pleomorphic areas with many bizarre large atypical cells, (e) areas with monotonous medium- to large-sized cells, (f) areas with increased infiltrating eosinophils, (g) cells with plasmacytoid appearance, (h) areas with clear large cells, and (i) areas with spindle-shaped cells with somewhat plasmacytoid features. High power examination (400x) of areas seen in (i) and (d) shows the variety of morphologies of the large atypical cells (j-r) with (j) lacunar cells, (k) multinucleated cells, (l) markedly hyperchromatic cells with dense eosinophilic cytoplasm, (m,n) bizarre cells with eosinophilic nucleoli, (o) Reed-Sternberg-like cells with smudgy eosinophilic nucleoli and dense ampophilic cytoplasm, (p) mummified cells, (q) large atypical cells with multiple clear nuclei, and (r) popcorn-like cells with small nucleoli.

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