Primary Diffuse Large B Cell Lymphoma of the Rectum Mimicking an Arteriovascular Malformation: A Case Report and Review

Abstract

Introduction: Lymphomas are malignant neoplasms of the lymphocyte cell lines. They mainly involve lymph nodes, spleen, and other non-hemopoietic tissues, and are classified as either Hodgkin's or non-Hodgkin's lymphomas (NHL) of B-lymphocyte or T-lymphocyte origin. According to estimates, in 2008, 66,120 new cases of NHL occurred in the United States. Gastrointestinal NHL account for 4-20% of all NHL. Approximately 0.2-0.6% of malignant lymphomas arise in the colorectal tract. Primary rectal NHL is rare, accounting for 0.2% of all rectal malignancies. We present a patient with a history of multiple admissions with presumed rectal arteriovascular malformations (AVMs) who was ultimately diagnosed with primary diffuse large B cell lymphoma of the rectum (DLBCL). Case: An 84-year-old Chinese male with past medical history of Hepatitis B and BPH presented to the ER with recurrent episodes of hematochezia. He denied abdominal pain, nausea, or vomiting. Previous colonoscopy for evaluation of the same symptoms had revealed only internal hemorrhoids and AVMs. He subsequently underwent a repeat colonoscopy which revealed a 3-cm ulcerated lesion immediately above the anal verge with persistent, active bleeding from the distal margin of the mass. APC thermal therapy was applied with adequate hemostasis. Biopsy and immunochemistry report was positive for CD5, CD20, PAX-5, BCL-2, BCL-6, consistent with DLBCL of the rectum. He subsequently underwent combined R-CHOP and radiation therapy with good results. Discussion: A thorough search of Pubmed and MEDLINE revealed fewer than 75 reported cases of primary B cell lymphoma of the rectum. The lack of specific complaints makes the diagnosis difficult to establish. Typically, the mean age at diagnosis is 55 years. Men are affected twice as often as women. The most common symptoms in more than half of patients are abdominal pain, weight loss, or changes in bowel habits. Lower gastrointestinal bleeding can be found in 13-20% of patients. The CHOP chemotherapeutic regimen (cyclophosphamide, doxorubicin, vincristine, and prednisone) remains the first line therapy, with surgery or radiation in some cases. Recent studies suggest that the addition of rituximab may lead to improved overall survival as well as disease progression. Conclusion: We present the case of an 84-year-old male with a history of multiple admissions for lower GI bleeding secondary to presumed AVMs, with a subsequent diagnosis of DLBCL. This rare malignancy can grow rapidly and should be included in the differential for recurrent lower gastrointestinal bleeding.