Imaging of atypical hemangiomas of the liver with pathologic correlation

Compared with the imaging features of typical hepatic hemangiomas, the imag ing features of atypical hepatic hemangiomas have not been well studied or well described. Knowledge of the entire spectrum of atypical hepatic hemang iomas is important and can help one avoid most diagnostic errors. A frequen t type of atypical hepatic hemangioma is a lesion with an echoic border at ultrasonography. Less frequent types are large, heterogeneous hemangiomas; rapidly filling hemangiomas; calcified hemangiomas; hyalinized hemangiomas; cystic or multilocular hemangiomas; hemangiomas with fluid-fluid levels; a nd pedunculated hemangiomas. Adjacent abnormalities consist of arterial-por tal venous shunt, capsular retraction, and surrounding nodular hyperplasia; hemangiomas can also develop in cases of fatty liver infiltration. Associa ted lesions include multiple hemangiomas, hemangiomatosis, focal nodular hy perplasia, and angiosarcoma. Types of atypical evolution are hemangiomas en larging over time and hemangiomas appearing during pregnancy. Complications consist of inflammation, Kasabach-Merritt syndrome, intratumoral hemorrhag e, hemoperitoneum, volvulus, and compression of adjacent structures. In som e cases, such as large heterogeneous hemangiomas, calcified hemangiomas, pe dunculated hemangiomas, or hemangiomas developing in diffuse fatty liver, a specific diagnosis can be established with imaging, especially magnetic re sonance imaging. However, in other atypical cases, the diagnosis will remai n uncertain at imaging, and these cases will require histopathologic examin ation.