Large and unusual presentation of gallbladder adenoma: A case report

BACKGROUND: Gallbladder adenoma is a relatively rare benign tumor with a potential for malignant transformation if found to be greater than 1 cm in size. CASE SUMMARY: Herein, we report a case of a 51-year-old female with large 3 cm × 3 cm mass of gallbladder adenoma that was misdiagnosed as adenocarcinoma due to its clinical presentation. Computed tomography and magnetic resonance imaging scans showed an irregularly shaped cauliflower-like lump in the gallbladder measuring 38 mm × 32 mm corresponding to a malignant tumor and several gallbladder stones with low diffusion-weighted imaging and equisignal of T1-weighted imaging and T2-weighted imaging; moreover, the CA 19-9 levels were very high (184.1 U/mL). Pathology reports after tumor resection showed adenoma with moderate epithelial atypia and moderate atypia in the focal area with fine pedicle and no clear infiltration. CONCLUSION: Computed tomography and magnetic resonance imaging scans need to be carefully scrutinized in certain rare cases of adenomas with abnormal imaging features.