Mass lesions of the liver.

Each of the six most common mass lesions of the liver may vary with respect to pathogenesis, clinical manifestations, natural history, usefulness of diagnostic tests, and the need for and value of surgical treatment. Despite these many variables, one broad generalization can be made: three lesions (cysts, cavernous hemangiomas, and focal nodular hyperplasia) usually are incidental findings that can be ignored, whereas three other tumors (adenomas, malignant hepatomas, and metastatic lesions) involve a threat to life that may be modified by surgical removal. This generalization, however, is not a guide to specific management because exceptions, atypical manifestations, diagnostic difficulties, and variations in the risks and limitations of surgical therapy are so common. The widespread use of new techniques for "imaging" has changed the responsibility of both the medical and the surgical hepatologist. Lessons of the past learned from the management of clinically evident symptomatic lesions have little usefulness in the management of small, "early," or indeterminate lesions. In these circumstances, physicians, surgeons, and radiologists must work in concert when a lesion is first found. Only then will clinically relevant tests be done that will ensure proper treatment of the patient.