Presentation
Incidental finding on abdominal ultrasound.
Patient Data
There is a hypoechoic well-defined lesion in segment IV, which has prominent internal vessels.
Segment IV hypervascular lesion that retains contrast on portal venous phase and transitional phases. On the delayed hepatobiliary phase, the lesion has a rim pattern of enhancement.
Macroscopy: Labeled "Segment 4B liver resection". A resection of hepatic tissue 45 x 38 x 35 mm with a roughened hepatic bed bearing multiple surgical staples. The opposing capsular surface is smooth, and violaceous, and somewhat distorted by a 36 mm area of tan, ovoid discolouration representing the underlying tumor. During the process of removal of the staples, some of the hepatic bed is sheared off. Resultant "False margin" inked red. Hepatic bed inked black. Capsule surface inked blue. Sectioning reveals a 38 x 33 x 30 mm lobulated tumor with an ill-defined border and a homogeneous tan cut surface with a central fibrous scar like area. The tumor is present at the hepatic resection margin in multiple areas, and also abuts the hepatic surface. Part processed.
Microscopy: Sections of liver show an unencapsulated lesion with a central region of scarring with adjacent fibrous collagenous tracts showing bile duct proliferation. Within the intervening tissues, there are trabeculae hepatocytes within which the hepatocytes show no evidence of nuclear atypia. Cell plates are compressed but up to 3 cells thick. There is focal steatosis and there is also focal chronic inflammation within the fibrous tracts. Portal tracts are not seen within the lesion. Kupfer cells are seen inlining the sinusoids and in sinusoids within the lesion. The lesion appears completely excised.
Opinion: Segment 4B liver resection–focal nodular hyperplasia, completely excised.
Case Discussion
This case shows a ring-type pattern of enhancement on the delayed hepatobiliary phase that can be encountered in focal nodular hyperplasia (FNH).