On imaging or histology, how might lymphoma be differentiated from inflammatory bowel disease?

• A. Lymphoma may present with diffuse mild thickening and inflammatory infiltrates
• B. Lymphoma may present with focal or nodular thickening and mass effect; histology shows neoplastic lymphocytes
• C. IBD shows mass effect
• D. They cannot be distinguished histologically

Answer: (C)

A key distinction is that lymphoma tends to form a mass that causes focal or nodular thickening, sometimes with a clear mass effect on imaging, and is confirmed histologically by sheets or clusters of neoplastic lymphocytes invading the mucosa and submucosa. This combination—a discrete mass on imaging and malignant lymphoid cells on biopsy—points to lymphoma rather than inflammatory bowel disease.

Inflammatory bowel disease usually shows diffuse or segmental mural thickening due to edema and inflammatory infiltrates, with chronic changes to the mucosa such as crypt distortion or granulomas in Crohn’s, but it does not typically produce a discrete mass of neoplastic lymphocytes. Therefore, the presence of a mass-forming lesion with neoplastic cells is the hallmark differentiator, rather than a mass effect being a feature of inflammatory disease.