Incidental gallbladder carcinoma: Utility of histopathological evaluation of routine cholecystectomy specimens.

Background: Incidental gallbladder carcinoma (IGBC) is rare cancer diagnosed during or after cholecystectomy done for benign gallbladder disease. The concern whether routine histopathological examination is needed for all cholecystectomy specimens still remains debatable.

Materials and Methods: Twenty patients diagnosed with IGBC over a period of 2 years were retrospectively reviewed. Clinical details including clinical presentation, preoperative ultrasound (USG) findings, and macroscopic features were retrieved. Diagnosis of IGBC was confirmed on microscopic examination, and staging was done using the tumor node metastasis staging system.

Results: Of the 4800 cholecystectomy specimens retrieved, diagnosis of IGBC was rendered in twenty cases (0.41%). Mean patient age was 50.65 years with a female preponderance. Preoperative USG detected an increase in wall thickness in six cases (30%) in contrast to gross examination which revealed the same in 55% (11/20) cases. Mucosal ulceration was observed in two cases (10%) of IGBC and seven cases (35%) did not reveal any preoperative or macroscopic findings suggestive of malignancy. Associated cholelithiasis was observed in 14 cases. Final diagnosis of IGBC was made on histomorphological assessment with tumor cells infiltrating the lamina propria in three cases (pT1b), muscularis propria in 15 cases (pT1b), and serosa in the remaining 2 cases (pT2).

Conclusion: IGBC is a clinical masquerader which often evades the eye of a radiologist and comes as pathological surprise. Histopathological examination of cholecystectomy specimens remains the gold standard for the detection of this occult, yet notorious malignancy and assessment of the depth of invasion in IGBC guide further management.