Gallbladder Follicular Lymphoma Mimicking Gallbladder Cancer

Enlarged polypoid gallbladder lesions should first be evaluated to rule out gallbladder cancer. Gallbladder lymphoma rarely develops, and gallbladder follicular lymphoma is seldom observed.

The case of a 70-year-old man with an enlarged polypoid gallbladder lesion and stable-sized multiple enlarged mesenteric lymph nodes is reported. No specific symptoms and obvious abnormalities were observed in laboratory data, such as tumor markers or soluble interleukin-2 receptor levels. The polypoid gallbladder lesion had enlarged from 10 mm to 15 mm in 1 year, had a slightly irregular surface, and showed moderate early enhancement with delayed washout on multiphase contrast-enhanced computed tomography (CT). The apparent diffusion coefficient on diffusion-weighted magnetic resonance imaging was 0.95×10^-3 mm²/s, indicating the high cell density and high water diffusion restriction. Positron-emission tomography/computed tomography revealed no increased fluorodeoxyglucose activity in the gallbladder lesion. Laparoscopic total cholecystectomy and excisional biopsy of the mesenteric lymph nodes were performed. Numerous polypoid lesions were detected in intraoperative contrast-enhanced ultrasonography with a high contrast effect. Gross specimens contained numerous polypoid lesions of various sizes. Immunohistochemical staining identified tumor lymphocytes positive for CD10, CD20, and BCL2 apoptosis regulator (BCL2), and CD23-positive fibroblastic reticulocytes forming a reticular network within the nodules. The gallbladder and mesenteric lymph nodes were finally diagnosed as grade 1 follicular lymphoma. The patient is being closely monitored every 6 months without medication.

Gallbladder follicular lymphoma is difficult to diagnose preoperatively, however, extra-regional lymph node swelling and relatively low apparent diffusion coefficients on magnetic resonance imaging can help its diagnosis.