PMC5688355_01
Endoscopic image of ulcerated polypoid lesion discovered in the terminal ileum during routine screening colonoscopy.
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A 2.0 cm polypoid, nonobstructing, ulcerated lesion was seen just inside the ileocecal valve (Figure 1).
Morphologic features of the ileal lesion. (a) Low-power image of an H&E stain shows a vaguely nodular infiltrate with several adjacent reactive secondary lymphoid follicles. (b) High-power image of an H&E stain shows scattered large cells with multilobated nuclei (lymphocyte predominant cells) in a background of small lymphocytes and occasional histiocytes.
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Sections from the ileal lesion showed expansion of the submucosa by a lymphohistiocytic infiltrate with a vaguely nodular pattern (Figure 2(a)). The nodules contained scattered large atypical cells in a background of small lymphocytes and occasional histiocytes (Figure 2(b)).
Immunoarchitecture of the ileal lesion. (a) Low-power image of an IgD immunohistochemical stain shows numerous positive cells within the nodules. The mantle zone of an adjacent reactive follicle is also seen (right). (b) Low-power image of a CD21 stain shows expanded follicular dendritic cell meshworks associated with the nodules.
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At low power, immunohistochemical stains showed that the nodules contained mostly CD20-positive B-cells that coexpressed IgD and were associated with expanded CD21-positive follicular dendritic cell meshworks (Figure 3).
Immunohistochemical features of the neoplastic cells. (a) High-power image of a CD20 immunohistochemical stain shows expression by the scattered large neoplastic cells. Numerous small B-cells in the background also are positive. (b) A PAX5 stain also shows positivity in the large neoplastic cells and small background B-cells. (c) An OCT2 stain shows strong nuclear staining in the neoplastic cells. (d) A PD-1 stain shows rosetting of the large neoplastic cells by small PD-1-positive T lymphocytes.
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At higher power, the large atypical cells were observed to express CD45, CD20 (Figure 4(a)), PAX5 (Figure 4(b)), OCT2 (Figure 4(c)), and BCL6. T-cells (Figure 4(d)). These immunophenotypic findings confirmed the diagnosis of NLPHL.