Hepatic adenoma and focal nodular hyperplasia: differential diagnosis and treatment.

The diagnosis of benign hepatic tumors as hepatic adenoma (HA) and focal nodular hyperplasia (FNH) remains a challenge for clinicians and surgeons. The importance of differentiating between these lesions is based on the fact that HA must be surgically resected and FNH can be only observed. A series of 23 female patients with benign liver tumors (13 FNH, 10 HA) were evaluated, and a radiologic diagnostic algorithm was employed with the aim of establishing preoperative criteria for the differential diagnosis. All patients were submitted to surgical biopsy or hepatic resection to confirm the diagnosis. Based only on clinical and laboratory data, distinction was not possible. According to the investigative algorithm, the diagnosis was correct in 82.6% of the cases; but even with the development of imaging methods, which were used in combination, the differentiation was not possible in four patients. For FNH cases scintigraphy presented a sensitivity of 38.4% and specificity of 100%, whereas for HA the sensitivity reached 60% and specificity 85.7%. Magnetic resonance imaging, employed when scintigraphic findings were not typical, presented sensitivities of 71.4% and 80% and specificities of 100% and 100% for FNH and HA, respectively. Preoperative diagnosis of FNH was possible in 10 of 13 (76.9%) patients and was confirmed by histology in all of them. In one case, FNH was misdiagnosed as HA. The diagnosis of HA was possible in 9 of 10 (90%) adenoma cases. Surgical biopsy remains the best method for the differential diagnosis between HA and FNH and must be performed in all doubtful cases. Surgical resection is the treatment of choice for all patients with adenoma and can be performed safely. With the evolution of imaging methods it seems that the preoperative diagnosis of FNH may be considered reliable, thereby avoiding unnecessary surgical resection.