Discussion:
The most common histologic subtype of NHL affecting the GI tract and colon is DLBCL. PRL usually presents with signs and symptoms suggestive of primary rectal carcinoma: weight loss, abdominal pain and lower gastro-intestinal bleeding [4]. Whatever the presentation, endoscopy with biopsy are the most valuable diagnostic tests. The majority of colorectal lymphomas are localised in the cecum or ascending colon [5]. As reported in the literature, colonoscopy showed in our case a budding rectal mass, and biopsy confirmed the diagnosis of DLBCL. Immunohistochemistry usually used to confirm diagnosis is CD20, CD79a, and CD10 [6]. CT scan is usually used to study tumor extension. Concentric rectal wall thickening with or without a regional lymph node involvement are frequently reported. Positron emission tomography (PET) is currently indicated in the diagnosis and disease follow-up [7]. The Ann Arbor staging system modified by Musshoff is widely used in tumor classification [8]. Given the rarity of the rectal localization, there is no standard treatment protocol. Chemotherapy remains the the main therapeutic modality [9].R-CHOP protocol including Rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone remains the most used protocol [10]. Several studies reveal a trend toward improved survival when surgery is used in combination with chemo- or radiotherapy [11]. In our case, we have treated patient with chemotherapy with a complete response. Jeong and al noted a significant difference in survival between patients with stages I-II and stage IV disease [5].