Diffuse large B-cell lymphoma of the colon with synchronous liver metastasis: a rare case report mimicking metastatic colorectal adenocarcinoma

BACKGROUND Primary colorectal lymphoma represents a rare minority among the colonic neoplasms. Early diagnosis is often difficult because of unspecific symptoms, with subsequent delays in diagnosis and management. We describe a rare case of colonic lymphoma presenting with synchronous liver metastasis. CASE PRESENTATION A 70-year-old male with a 6-mo history of vague abdominal pain, constipation and melena was referred to our hospital. Computed tomography scan of abdomen revealed the presence of a mass along the proximal ascending colon. Colonoscopy biopsy showed external compression of the cecum with two ulcerations of mucosa, but it was not consistent for a definitive diagnosis. Because the difficulties in the preoperative pathological diagnosis, the high risk of bowel obstruction and the correlated hemorrhagic risk, the patient underwent a right hemicolectomy associated with locoregional lymphadenectomy and liver resection.The surgically resected right colon and liver tumors were all immunohistochemically diagnosed as diffuse large B-cell lymphomas (DLBCL). The patient refused any other antineoplastic treatment; he is alive and free of disease at 3 years after initial diagnosis. CONCLUSIONS Primary colonic lymphomas represent a rare minority among the colonic neoplasms. Their correct pre-operative identification is crucial for the design of treatment. This case highlights the difficulty in diagnosing of primary colonic lymphoma. To our knowledge, this is the first report of a colonic lymphoma presenting with a colonic mass and a synchronous liver metastasis.