PMC8462868_01
Row A: CT scan four months prior to recto-sigmoid DLBCL diagnosis showcasing mild irregular wall thickening of the recto-sigmoid colon (red arrows) and bladder (yellow arrow). Row B: CT at the time of diagnosis demonstrating significant irregular wall thickening of the recto-sigmoid colon with a large stool-containing collection superimposed on matted loops of inflamed large bowel (blue circle). Center image exhibits a colo-colonic fistula between cecum and rectum (green circle). Third image displays worsening circumferential wall thickening of the bladder (yellow arrow). Row C: Six months post-chemotherapy CT illustrates less wall thickening of the sigmoid colon in the colorectal junction with a smaller area of involvement. The tumor burden is moderately to significantly lower due to smaller soft tissue involvement
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A CT of the abdomen and pelvis with contrast revealed mass-like mural thickening of the sigmoid colon concerning for colorectal neoplasm with a new large stool-containing collection superimposed on matted loops of inflamed large bowel suspicious for a contained perforation and a colo-colonic fistula (Figure 1). Compared to CT of the abdomen and pelvis four months prior, there had been an interval worsening of the irregular wall thickening of the recto-sigmoid colon and increase in bladder wall thickening (Figure 1).
A, B: Sections of the rectosigmoid mass biopsies demonstrate ulcerated and inflamed colonic mucosa with a distinct population of large mononuclear cells within the lamina propria. Neoplastic cells are positive for C: CD20, D: BCL6 (~40%) and E: MUM1, and are negative for F: CD10 (hematoxylin-eosin, original magnification X100 [A] and X400 [B]; original magnification X400 [C, D, E, F])
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Pathologic review revealed Diffuse large B-cell lymphoma (DLBCL), activated B-cell type (ABC, non-germinal center) in recto-sigmoid biopsies (Figure 2).
Row A: Pre-chemotherapy PET scan showed intense FDG activity in the sigmoid colon and rectum, mesenteric lymph nodes, and the left lateral posterior aspect of the prostate. Row B: Six months post-chemotherapy PET scan denotes decreased intensity of FDG activity in the sigmoid colon and colorectal junction and resolution of small lesions in the lower abdomen and pelvis
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PET/CT scan was obtained prior to initiation of chemotherapy to complete staging. PET scan revealed intense foci of FDG activity in the sigmoid colon and rectum, several pulmonary nodules, the left lateral posterior aspect of the prostate and mesenteric lymph nodes, suspicious for malignant involvement (Figure 3). There was resolution of the small lesions in the lower abdomen and pelvis (Figure 3).