case_images: PMC7596907_01
case_images: Contrast CT of the abdomen before and after chemotherapy.. Upper column: Imaging before chemotherapy. The abdominal cavity was filled with thickened serous membranes and mesenteries, and all intestines were embedded in these membranes with an unclear intestinal configuration. Tumor formation was not noted. Arrows indicate markedly enlarged intestines filled with air (not free air). The amount of ascites was modest.. Lower column: Imaging after chemotherapy. The thickening of the serous membranes was reduced and the outlines of individual intestines could be visualized with slightly thickened intestinal walls.
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case_images: Abdominal CT showed diffusively thickened serous membranes, and it was difficult to identify the intestinal configuration (Figure 1). The outline of the individual intestines could be visualized on CT (Figure 1).
case_images: Macroscopic features of the colon at autopsy. The serosal membrane showed patchy fibrous thickening, and the intestinal wall was edematous.
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case_images: Macroscopic features of the colon showed patchy fibrous thickening of serosal membranes and an edematous intestinal wall (Figure 2).
case_images: Microscopic examinations at low magnification of the colon revealed that atypical lymphoid cells infiltrated the whole intestinal wall layer, particularly in the mucosa and subserosa. Arrows A and B indicate the mucosa and subserosa, respectively (H-E staining, x20). Arrowheads indicate the muscular layer.
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case_images: Microscopically, marked infiltrations of lymphoma cells were observed in the peritoneum, mesenteries, mucosa of the small and large intestines, and pleural serous membrane, as shown in Figure 3 from the large intestine, in which the infiltration of abnormal lymphocytes was conspicuous in the mucosa and subserosa (Figure 3).
case_images: Immunohistochemical examination of the peritoneum and colonal mucosa at autopsy.. These abnormal lymphoid cells were positive for CD3 (A) and CD4 (faintly) (B) but negative for CD20 (C), CD8 (D), and CD56 (E) (x400 for CD3 andx200 for the rest).
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case_images: This invasion was massive and space-occupying (Figure 4A/B). Lymphoma cells were small and some of them showed nuclear atypism (Figures 4A/5A). Residual crypts were intact without epitheliotropism by lymphoma cells (Figure 4B).
case_images: Histopathological examination of the peritoneum and colonal mucosa at autopsy.. A: The peritoneum was diffusely infiltrated by small lymphoid cells. These cells had round nuclei with slight atypism and a high N/C ratio. H-E staining, x400.. B: The colonic mucosa was also densely infiltrated by the same small atypical lymphoid cells. Epitheliotropism of these lymphoid cells was not observed. H-E staining, x200.
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case_images: Immunohistochemical examination demonstrated that these cells expressed CD45RA/RO, CD3, CD4 (faintly), CD5, and CD7 but not CD20, CD8, CD10, CD56, or perforin 1 (Figure 5; data not shown for CD45RA/RO, CD5, CD7, CD10, and perforin 1).