Benign lesions of the liver.

Although many hepatic lesions can overlap significantly in their imaging appearance, an imaging approach that is based upon identifying the pathologic and functional components of a lesion can aid in distinction from other entities. In this manner, the diagnostic evaluation can be tailored using the appropriate imaging modality for the lesion at hand. An understanding of the benign liver lesions based on the cellular line of origin and subsequent functional components aids in grasping their expected imaging appearance and may aid in their distinction from malignant tumors. Thus, an imaging approach leading to diagnosis of these tumors should be based on this underlying knowledge of the functional components and cells within the lesion to be studied. For lesions with Kupffer's cell activity, such as FNA, Tc-99m sulfur colloid scan or MR imaging with SPIO may yield the most diagnostic information. For lesions such as hepatic cysts or angiomyolipoma, the diagnosis is usually not a dilemma. For hemangiomas, the most commonly encountered benign hepatic lesion, distinction from other entities may be readily apparent from the initial CT scan or US examination, or it may require additional evaluation with MR imaging. Finally, for other lesions with many cellular components, such as HCA, the imaging findings may not be specific enough by any modality to preclude tissue diagnosis. In any case, it is important to know the diagnostic accuracy and limitations of the imaging modalities available for assessment of any given benign hepatic mass.