37-year-old Nihaar was experiencing abdominal pain when he went for an ultrasound. During the investigation, the radiologist told him he has gallbladder stones. On repeat ultrasound examination from another hospital, he was told he has polyp. He visited a doctor with the report and was told that
are sometimes mistaken for polyp and vice versa.
Before we get into the whole question of misdiagnosis, first let us understand the difference between the two.
Dr Suraj Bhagat, Senior Consultant, Department of Gastroenterology & Hepatology, Amrita Hospital, Faridabad shares, “Gallbladder stones are frequently seen in the population as an incidental finding on routine abdominal ultrasound or when a patient presents with symptoms and complications of gallstone disease. An abdominal ultrasound is highly sensitive for detecting gallstones more than 2 mm, although it may miss stones smaller than this size in many cases.
Dr Anant Kumar, Chairman – Urology Renal Transplant and Robotics, Max Super Speciality Hospital, Saket tells, “Gallstones are hard, pebble-like cholesterol or pigment deposits that form inside the gallbladder and found in approximately 4% of the Indian population. Gallbladder polyp can be misdiagnosed with gallbladder stone.”
Like gall bladder stones, gallbladder polyps usually do not cause symptoms and are detected incidentally when ultrasound is done for other reasons. Only a minority of polyps have a risk of malignancy. These polyps are characterized on the basis of specific imaging features (on abdominal ultrasound or endoscopic ultrasound), size, vascularity, rate of growth and clinical profile of the patient. Polyps that are greater than 1 cm in size, especially with rapid increase in size, those that cause symptoms or have associated gallstones, are more likely to have malignant transformation and require cholecystectomy. Polyps that are 6-9 mm in size require periodic surveillance with ultrasound for increase in size and polyp characteristics.”
On condition of anonymity, an internal medicine specialist shared how he has heard of cases where the doctor realised in OT that what they are operating is not gallstones but actually polyps and vice versa.
Dr Suraj explains in detail, “Stones will typically show acoustic shadowing on ultrasound and this finding is very accurate to diagnose stones. Gallbladder polyp is diagnosed when there is a mucosal protrusion or projection into the lumen of the gallbladder. Similar to gallstones, polyps may be found incidentally on routine abdominal imaging. Most polyps are benign non-neoplastic lesions. A small minority of the polyps are neoplasms, like adenomas, which may have malignant potential at some stage. Also, it is not uncommon to find gallstones in patients who have polyps. On abdominal ultrasound, polyps are fixed to the gallbladder wall or have limited mobility, unlike gallstones which freely change their position with specific maneuvers. In addition these lesions do not have acoustic shadowing like gallstones. In most cases there is no difficulty in diagnosing gallbladder stones and polyps on ultrasound. Sometimes it may be difficult to differentiate between a polyp and a small soft adherent calculus or sludge because the latter has no acoustic shadowing and mobility may also be limited. Endoscopic ultrasound may be helpful in some of these patients where there is diagnostic difficulty. In suspicious lesions, CT scan or MRI may be needed for characterizing the lesion.”
Gallbladder cancer may develop in 1-3% of patients with gallbladder stones. This risk of cancer is much higher for patients with specific imaging features (like porcelain gallbladder) and in high risk populations (some ethnic groups); these patients are advised prophylactic cholecystectomy, shares Dr Suraj.
People with incidentally detected polyps, who have been advised surveillance with ultrasound, should strictly follow this advice. Although malignancy will develop in a small minority of patients, surveillance is the recommended method to identify these patients. Timely detection of change in polyp size and characteristics is imperative so that cholecystectomy can be performed to remove the lesion, he adds.