Primary Colonic MALT Lymphoma: A Very Rare Cause of Iron Deficiency Anemia

Abstract

Purpose: MALT lymphoma involves the colon less than 20% of the time. This is mostly in a secondary fashion, and less than 5% of primary colonic lymphomas are of the MALT subtype. This amounts to less than 0.1% of all colorectal malignancies. A 53-year-old woman with diabetes, hypertension, and CHF presented for colonoscopy to further evaluate iron deficiency anemia. She was asymptomatic, specifically denying melena or hematochezia. Family history was negative for colorectal polyps or cancer. The abdomen was soft, with no palpable masses. Colonoscopy revealed a 7 x 5-cm round, firm, submucosal, friable mass at the hepatic flexure. It occupied the entire lumen, but was able to be traversed. Biopsies were consistent with marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT). CT showed invasion of the adjacent adipose tissue with regional lymphadenopathy. EGD showed mild H. pylori-positive gastritis and duodenitis, but there were no findings to indicate gastric MALT, and she was treated with antibiotics. Bone marrow biopsy showed malignant lymphoma invasion. R-CHOP was initiated for disseminated disease, but held after two cycles due to decompensated CHF. Follow-up PET scan revealed no activity in the hepatic flexure, and she will have a colonoscopy and CT scan for surveillance. The location of the lesion in the hepatic flexure in our case is consistent with the reported mild-to-moderate predilection for the proximal colon. One quarter to one third of non-gastric MALT lymphomas are disseminated at diagnosis. More than 80% of patients with intestinal MALT present with symptoms referable to the GI tract, but despite the large size of the tumor, our patient was asymptomatic and already had signs of invasion. Regardless of treatment modality or stage at diagnosis, the disease typically follows an indolent course with excellent 5-year survival rates of 85-100%. However, the relapse rate in non-gastric MALT lymphoma approaches 50%, emphasizing the need for lifelong follow-up in these patients.Figure