Mimicking an Intraluminal Lesion: A Case Report on Mantle Cell Lymphoma.

Mantle cell lymphoma is typically an aggressive, rare form of non-Hodgkin lymphoma that arises from cells originating in the "mantle zone." Here, we describe a case of mantle cell lymphoma associated with gastrointestinal bleeding, which was worked up as a possible gastrointestinal lesion or intraluminal pathology. The patient presented with symptomatic microcytic anemia associated with a positive guaiac fecal test. However, after an extensive workup to elucidate the symptomatic anemia's etiology, mantle cell lymphoma associated with a positive guaiac test was the culprit. Usually, mantle cell lymphoma is diagnosed at a later stage involving the bone marrow and gastrointestinal tract.