An Unexpected Case of Metachronous Diffuse Gastrointestinal Mantle Cell Lymphoma and Aggressive Metastatic Colonic Adenocarcinoma

Abstract

Purpose: A 70-year-old woman was evaluated for hematochezia. Past history included hypertension. Physical examination was normal. Colonoscopy revealed pancolonic multiple erythematous polypoid lesions. Upper endoscopy showed nodular gastroduodenal mucosa. Diffuse gastrointestinal (GI) mantle cell lymphoma (MCL) was confirmed with histopathological and immunohistochemical studies. Staging PET/CT scan showed increased FDG uptake in gastric fundus and colon but no nodal involvement, suggesting primary GI MCL. Peripheral blood smear and bone marrow aspirate were normal. Combination chemotherapy consisted of 6 cycles R-CHOP regimen and maintenance rituxan. Endoscopy and PET/CT at 6 months confirmed successful response. Surveillance PET/CT at 12 months showed abnormality in the cecum. Colonoscopy revealed single 3 cm friable ulcerated cecal lesion suspicious for recurrence of MCL. Biopsy showed poorly differentiated adenocarcinoma. Right hemicolectomy revealed T4N2M0 with recurrence of MCL in appendix. After slow post-operative recovery, a restaging PET/CT was done prior to adjuvant chemotherapy. Multiple new hepatic lesions were confirmed as colon cancer metastases. After discussing treatment options, patient opted for hospice care. While colorectal cancer is a common GI malignancy, primary GI lymphoma is not. MCL often invades the GI tract but primary GI MCL is rare. Most frequent endoscopic finding of MCL is multiple lymphomatous polyposis, a rare entity accounting for 2% of primary GI lymphomas. MCL is a moderately aggressive disease. Median survival is 3 years. Most patients have advanced disease at diagnosis. 50% have bone marrow infiltration, 25% have involvement of GI tract. Leukemic transformation occurs in 25%. Tumor cells express pan-B-cell markers and the T-cell marker CD5. Overexpression of cyclin D1 has been noted. Combined chemotherapy, chemo-immunotherapy, peripheral stem cell transplantation are treatments of choice. Concomitant GI tract metachronous malignant lymphoma and adenocarcinoma are rare. Less than ten cases of synchronous GI MCL and colon cancer have been reported in literature. To our knowledge there has been no report of diffuse primary GI MCL with metachronous aggressive colon cancer detected incidentally. Further investigation of a potential relationship between MCL and colon cancer is warranted. Recognizing a relationship may help with accurate management and surveillance. Definitive studies are required to expand our findings and study the genetic basis of these observations.