Prevalence of adenoma of gallbladder, ultrasonographic and histological assessment in a retrospective series of 450 cholecystectomy

OBJECTIVES: Adenomyomas of the gallbladder (GA) are difficult to examine during standard ultrasound examination of the abdomen. They sometimes undergo malignant transformation and their optimal management still remains a problem. The authors have aimed to investigate the ultrasonographic (US) and histopathological prevalence of GA focusing on the diagnostic performance of US examination. MATERIALS AND METHODS: A retrospective series of 450 consecutive patients who underwent cholecystectomy is reported. Data regarding characteristics of the patients, US and histology examination of the gallbladder were collected. Sensitivity, specificity, positive and negative predictive values of US were calculated with respect to histological examination of the gallbladder. RESULTS: The study group consisted of 261 female and 189 male. US scan detected adenomyomas in 22 patients, confirmed by histopathology in 13 and found to be not present in 9. Incidental adenomyomas were found in 16 patients of 428 who underwent cholecystectomy for gallstones. Prevalence was 4.9% and 6.4% for US scan and histopathology respectively. US scan showed sensitivity of 43.3% (c.i.:25.4%-62.5%), specificity of 97.8% (c.i.:95.9%-99%) with a positive predictive value of 59% (c.i.:36.3%-79.2%) and with a negative predictive value of 96.2% (c.i.:93.7%- 97.6%). On histopathology, adenomyomas localized in the fundus were predominant. Two female patients with adenomyomas of the fundus (diameter 5 mm) and single stone showed intestinal metaplasia with high-grade dysplasia. CONCLUSIONS: The diagnosis of gallbladder adenomyomas by US scan still remains a problem because of its low sensitivity, which is mainly due to the association with gallstones. At present, the selection of patients requiring cholecystectomy is still controversial, surgery is indicated in the presence of GA>1cm and if symptomatic cholelithiasis is present, with respect to polyps smaller than 1cm the presence of diameter increase, the association of thickening (>3mm) of the gallbladder wall and the presence of dysmorphism at follow-up with US are widely considedered as indications for surgey. In our study histopathological findings in the perilesional mucosa confirm the hypothesis of a metaplasia-dysplasia-carcinoma sequence already shown in the colon-rectum, even if no cancer were found. According with our results surgery is proposed when GA is associated with cholelithiasis in all cases because of the increased risk of malignancy development, independently from the dimension of lesion.