Ultrasonographic features of polypoid myoglandular hyperplasia of the gallbladder, that were difficult to distinguish from early gallbladder cancer.

The patient, a 50-year-old man, had been followed up by a neurologist under the diagnosis of mitochondrial encephalomyopathy. A gallstone detected by abdominal ultrasonography (US) had been present for several years, but localized protrusions of the gallbladder wall were first seen at the fundus in May 1995. Endoscopic US after abdominal US showed several small protruding lesions with maximum diameters of about 7 mm. These lesions had irregular surfaces and low internal echogenicity. An external high echoic layer, which represented the subserosa of the gallbladder, was intact. The lesions were enhanced on CT scanning. No anomalies of the pancreaticobiliary system were detected by endoscopic retrograde cholangiopancreatography. Selective cystic arteriography disclosed slight staining of the body of the gallbladder. Because of the high possibility of gallbladder carcinoma, surgery was carried out. Macroscopy showed several elevated or protruding lesions up to 7 mm in diameter at the fundus of the resected gallbladder. The lesions had rough surfaces and were yellowish in color. Histologic examination showed the lesions to be covered by columnar epithelium, and no cellular dysplasia was detected. Because both pyloric gland-like hyperplasia and smooth-muscle proliferation were observed, the lesions were diagnosed as polypoid myoglandular hyperplasia. We have encountered four other similar cases of this tumor. Accurate diagnosis of these lesions before surgery is sometimes difficult, and the sonographic features of myoglandular hyperplasia have to be recognized in order to distinguish it from early gallbladder cancer.