Primary diffuse large B-cell lymphoma of the sigmoid colon

Abstract

Introduction: Extranodal lymphomas are commonly encountered in the gastrointestinal tract but lymphomas of colon and rectum are rare. Non-Hodgkin lymphoma is the most common type of colonic lymphoma and represents less than 0.5% of colorectal neoplasms. Chemotherapeutical agents are gateway to disease remission and sometimes cure in most patients but surgery may be necessary in emergent situations.

Case presentation: A 77-year-old male patient presented with abdominal discomfort, constipation, and obstructive defecation symptoms. Radiological imaging revealed a mass in the sigmoid colon extending towards the rectum. Colonoscopy was performed and biopsy of a nearly 10 cm ulcerovegetative lesion was obtained. Histological examination following biopsy revealed it to be a diffuse large B-cell lymphoma of the sigmoid colon. There was no indication for surgery and the patient was referred to medical oncology clinic for chemotherapy treatment.

Discussion: Non-Hodgkin lymphoma is a lymphoproliferative disorder with the diffuse large B cell lymphoma (DLBCL) being the most common subtype. The DLBCL subtype is rarely observed in the colon and rectum. Chromosomal abnormalities are involved in the pathophysiology and gene rearrangements lead to adjustments in lymphocyte function and differentiation.

Conclusion: In this case report, we present a rare presentation of a Non-Hodgkin lymphoma presenting in the sigmoid colon. The disease can present with nonspecific symptoms and various imaging modalities along with histopathological evaluation is necessary for the correct subtyping of lymphoma. Chemoradiotherapy is key for treatment, and surgery is usually reserved for cases of obstruction, perforation, or bleeding.

Keywords: Colonic obstruction; Diffuse large B-cell lymphoma; Primary colonic lymphoma.

Fig. 1

A) The abdominal CT scan showing a mass protruding and nearly obstructing inside the bowel lumen, B) PET scan showing primary tumor location with multiple infra- and supra-diaphragmatic lymph node involvement.

Fig. 2

A) Normal colonic mucosa and diffuse tumoral infiltration in lamina propria (H&E, 20× magnification), B) atypical lymphoid cells with irregular round nuclei, dark chromatin, distinct central nucleoli (H&E, 400× magnification), C) Mum-1 positivity suggesting a non-germinal center B-cell DLBCL subtype (ABC method 400× magnification), D) atypical lymphoid cells staining positive for CD20 (ABC method 400× magnification).