THE RADIOLOGIC AND PATHOLOGICAL SPECTRUM OF BILIARY HAMARTOMAS

OBJECTIVE. The purpose of our study was to correlate the spectrum of r adiologic and pathologic findings in a series of patients with biliary hamartomas and known extrahepatic malignancy. MATERIALS AND METHODS. Biliary hamartomas were diagnosed in 18 patients with a primary malign ant lesion who had liver biopsy for evaluation of possible metastatic disease. Prebiopsy imaging studies included CT in 16 patients and sono graphy in 11. Imaging studies were reviewed retrospectively and correl ated with findings at surgery and on pathologic examination. The hamar tomas were classified histologically by the degree of cystic dilatatio n of bile ducts within the lesion. RESULTS. Radiologically, biliary ha martomas presented a spectrum of findings including one or two circums cribed lesions (5-10 mm in diameter) in four patients; multiple (about five) lesions (approximately 5 mm each) in one patient; innumerable t iny, nearly uniform (2-5 mm) lesions in two patients; and innumerable lesions of varying size (2-15 mm) in three patients. Among the patient s with innumerable lesions, the nodules were either uniformly or nonun iformly distributed throughout the liver. in all cases, the lesions we re hypodense on contrast-enhanced CT scans and hypoechoic on sonograms . In eight patients, the lesions were not visible by imaging but biops ies were done at surgery when single or multiple tiny nodules were not ed on the liver surface. The diagnosis was made by either wedge or cor e-needle biopsy; fine-needle aspirations were nondiagnostic. Pathologi c examination revealed single or multiple hamartomas of varying sizes ranging from solid to largely cystic lesions; the degree of cystic dil atation did not correlate with imaging findings. Visibility on imaging correlated with larger lesion size; small surface lesions were usuall y occult. CONCLUSION. Biliary hamartomas cause single or multiple nons pecific hepatic lesions that may mimic metastases. This diagnosis shou ld be considered in patients with a primary malignant tumor when singl e or multiple small hepatic lesions are seen, regardless of uniformity of size or distribution.