Mucin-containing Rokitansky-Aschoff sinuses with extracellular mucin deposits simulating mucinous carcinoma of the gallbladder.

[carcinoma of the gallbladder]

Rokitansky-Aschoff sinuses (R-As ) are epithelial invaginations that extend down the gallbladder wall through the smooth muscle gaps and by this pathway they reach the subserosal connective tissue . We report here 5 cases of mucin-containing R-As that ruptured , and as a result , extracellular mucin escaped into the adjacent stroma . They were compared with 10 mucinous carcinomas of the gallbladder . Three cases of mucin-containing R-As accompanied by abundant extracellular mucin deposits with epithelial strips , glands and papillary structures were misinterpreted as mucinous carcinomas . Because of this , the patients were subjected to a second unnecessary radical surgical procedure . In the remaining 2 cases , the extracellular mucin associated with R-As was acellular and regarded as focal . Three patients were men and 2 women whose ages ranged from 2 to 71 years (average age 52 y ). The youngest patient was a 2 -year -old boy in whom the mucin-containing R-As were discovered incidentally by magnetic resonance imaging . He was later diagnosed with metachromatic leukodystrophy . The remaining 4 patients complained of right upper quadrant pain and had a thickened gallbladder wall identified by computed tomography and magnetic resonance imaging . There were gallstones in 3 patients . The R-As located in the lamina propria contained mucin but were not cystically dilated whereas those located in the subserosa were mucin-filled and often cystically dilated . Detached fragments of biliary epithelium , small glands , and papillary structures lacking cytologic atypia and mitotic figures were identified in the abundant mucin deposits located in the subserosa of 3 cases . The overlying surface gallbladder epithelium exhibited papillary hyperplasia with focal intestinal metaplasia in 2 patients , one of which had metachromatic leukodystrophy . The lack of reactivity for carcinoembryonic antigen and p 53 and the low proliferative activity as measured by MIB-1 labeling index provided additional support to the benign nature of the lesion . Clues to separate mucin-containing R-As from mucinous carcinoma are provided . All 5 patients with mucin-containing R-As are disease free 8 months to 7 years after surgery (median follow-up of 39 mo ).