Clinical relevance of gallbladder polyps; is cholecystectomy always necessary?
Madelon J.H. Metman, Pim B. Olthof, Johannes B.C. van der Wal, Thomas M. van Gulik, Daphne Roos & Jan Willem T. Dekker
International Hepato-Pancreato-Biliary Association
DOI: https://doi.org/10.1016/j.hpb.2019.08.006
Gallbladder polyps are lesions of the gallbladder wall that protrude into the gallbladder lumen. They are commonly seen at ultrasound of the abdomen with a prevalence of 0.3 to 9.5%3,5. After cholecystectomy, polyps are observed in 0.004 to 13.8% of specimens3.
The differential diagnosis for a gallbladder polyp is wide and includes pseudotumours, in addition to benign and malignant tumours. Pseudotumours include cholesterol polyps, focal adenomyomatosis and inflammatory lesions that can be caused by infection2. Sludge is another potential mimic of a polyp. The literature estimates 30% of polyps are adenomatous polyps of the gallbladder, which have potential for malignant transformation. Patients with gallbladder carcinoma have a poor five-year survival rate of less than 5% due to a hidden and rapid progression of spread, which makes most disease unresectable at diagnosis4. Cholecystectomy is favoured for patients who are deemed to have malignant potential of a gallbladder polyp.
Most gallbladder polyp guidelines advocate for cholecystectomy if the polyp size at ultrasound is larger than or equal to 10 mm, or if the size has increased beyond a threshold during ultrasound surveillance2.
This study looks at the correlation between ultrasound and histopathological findings after cholecystectomy for suspected gallbladder polyps. A retrospective analysis was performed at two Dutch institutions for all cholecystectomies performed between January 2010 and August 2017, with a total of 3547 operations. Of these 110 were performed for suspected gallbladder polyps. 2 patients were excluded due to a known diagnosis of primary sclerosing cholangitis, which is known to increase malignant potential of polyps. Most patients (60%) had multiple polyps; median diameter 10 mm. 54 patients underwent ultrasound surveillance with an increase in growth of their polyps prompting cholecystectomy.
Surprisingly, most pathological specimens (65%) did not identify any macroscopic abnormality. Polyp-like lesions were observed in 22 (20%) of the specimens. The remaining specimens showed cholesterolosis and irregular foci of the gallbladder wall. Three pyloric gland adenomas were identified. The remaining specimens showed benign entities. None of the pyrloric gland adenomas had features of dysplasia or malignant transformation.
Out of the 108 operations, adverse events were recorded for 3 patients and classified as Dindo IIIa (complications requiring surgical, endoscopic or radiological intervention) or higher. The adverse events were sepsis secondary to bile leak, re-admission for percutaneous drainage of a biloma and surgery for an incarcerated trocar hernia.
This study reflects similar findings observed in the literature, which is that most gallbladder specimens following surgery for suspected gallbladder polyps predominantly showed pseudopolyps with no malignant potential. Pyloric gland adenomas have an unknown risk of malignant transformation. In a separate study of 165 polyps with pyloric subtype there were 44 showing high grade dysplasia and 2 showing adenocarcinoma1. In this same study 48 had no abnormality and 51 had cholesterolosis.
There are limitations to only using ultrasound assessment, other techniques such as contrast enhanced ultrasound, endoscopic ultrasound and MRI can have a role to help differentiate between benign from malignant polypoid gallbladder, although there is a lack of evidence for their use. Clinicians face a challenge to counsel patients about their suspected gallbladder polyps without a strong evidence base, as currently there is a poor correlation between imaging and histopathologic findings, and a high probability of no abnormality after surgery. Ongoing studies are attempting to improve our understanding, but most large studies are from Asian centres with a higher incidence of biliary malignancy compared to Western centres. The Netherlands is currently recruiting for a national prospective study (NTR7198), which will hopefully improve guidance.
This small study of 108 patients highlights a weak correlation between ultrasound and histopathology findings for suspected gallbladder polyps based on current guidelines, which ultimately leads to a high proportion of unnecessary operations. Laparoscopic cholecystectomy is a relatively routine procedure with a small but significant potential to cause harm. The hope is to develop better guidance and use of imaging to select the correct patients for surgery.
References:
- Albores-Saavedra, J., Chablé-Montero, F., González-Romo, M. A., Ramírez Jaramillo, M., & Henson, D. E. (2012). Adenomas of the gallbladder. Morphologic features, expression of gastric and intestinal mucins, and incidence of high-grade dysplasia/carcinoma in situ and invasive carcinoma. Human Pathology, 43(9), 1506–1513. https://doi.org/10.1016/j.humpath.2011.11.011
- Elmasry, M., Lindop, D., Dunne, D. F. J., Malik, H., Poston, G. J., & Fenwick, S. W. (2016). The risk of malignancy in ultrasound detected gallbladder polyps: A systematic review. International Journal of Surgery, 33, 28–35. https://doi.org/10.1016/j.ijsu.2016.07.061
- Kratzer, W., Haenle, M. M., Voegtle, A., Mason, R. A., Akinli, A. S., Hirschbuehl, K., Schuler, A., & Kaechele, V. (2008). Ultrasonographically detected gallbladder polyps: A reason for concern? A seven-year follow-up study. BMC Gastroenterology, 8(1). https://doi.org/10.1186/1471-230x-8-41
- Mellnick, V. M., Menias, C. O., Sandrasegaran, K., Hara, A. K., Kielar, A. Z., Brunt, E. M., Doyle, M. B. M., Dahiya, N., & Elsayes, K. M. (2015). Polypoid Lesions of the Gallbladder: Disease Spectrum with Pathologic Correlation. RadioGraphics, 35(2), 387–399. https://doi.org/10.1148/rg.352140095
- Park, J. K., Yoon, Y. B., Kim, Y.-T., Ryu, J. K., Yoon, W. J., Lee, S. H., Yu, S.-J., Kang, H. Y., Lee, J. Y., & Park, M. J. (2008). Management Strategies for Gallbladder Polyps: Is It Possible to Predict Malignant Gallbladder Polyps? Gut and Liver, 2(2), 88–94. https://doi.org/10.5009/gnl.2008.2.2.88
Dr Matthew Gale is a 5th year radiology registrar at the Queens Medical Centre, Nottingham, UK. His interests include gastro-intestinal, hepato-pancreato-biliary radiology and general and non-vascular intervention.
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