An Exophytic Ileocecal Mass: Diffuse Large B-Cell Lymphoma Diagnosed by Colonoscopic Biopsy

A 63-year-old man with no relevant comorbidities presented with 6 months of generalized abdominal pain, a 25-lb unintentional weight loss, and nocturnal fever. Laboratory testing showed microcytic hypochromic anemia with hemoglobin of 10.4 g/dL, low serum iron, and elevated lactate dehydrogenase of 490 U/L. Contrast-enhanced abdominal CT demonstrated an infiltrative mass involving the cecum and right colon, with extrinsic ureteral compression and right hydronephrosis. The appearance was concerning for an ileocecal malignancy, with lymphoma remaining in the differential diagnosis.

Colonoscopy revealed a large exophytic, endoluminal lesion arising from the ileocecal valve. Its surface was irregular and lobulated, with marked distortion of the local anatomy, while the remaining examined colonic mucosa was unremarkable. Multiple targeted biopsies were obtained.

Histopathology showed infiltration of the lamina propria by medium-to-large atypical lymphoid cells. Immunohistochemistry was positive for CD20 and supported a germinal-center phenotype; CD10 expression and Ki-67 nuclear labeling were also demonstrated. The findings established diffuse large B-cell lymphoma (DLBCL) without a double-expressor phenotype. Baseline PET/CT demonstrated metabolically active thickening of the cecal/ileocecal region.

The patient was referred to Hematology and received six cycles of R-CHOP. Follow-up PET/CT showed disappearance of the previously hypermetabolic intestinal lesions, consistent with a complete metabolic response.

Discussion

The practical lesson is that a lobulated, exophytic ileocecal mass should not automatically be approached as adenocarcinoma. Colorectal lymphoma may involve the ileocecal region and can present with a polypoid or mass-like morphology. Careful endoscopic inspection and adequate targeted biopsies can establish the diagnosis before definitive treatment planning.

References

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