Presentation
Acute abdominal pain, concerning for cholecystitis, despite atypical demographics.
Patient Data
There was no sign of cholecystitis.
However, fortuitous finding of a voluminous left lobe subcapsular liver mass, with internal vascularization on Doppler. The mass is isoechoic to the liver. There could be a central scar.
MRI confirms a voluminous subcapsular liver mass involving segments 2 (mostly) & 3. This mass is iso-intense to the parenchyma on pre-contrast T1 & T2 weighted images. It enhances avidly on the arterial phase and shows a central, non enhancing, scar. On T1 C+ late phase, the mass is iso-intense to the liver parenchyma, and on the 10 minutes late phase, the central scar enhances frankly.
The findings are typical of focal nodular hyperplasia.
Case Discussion
This is a classic case of FNH on US & MRI. It shows a central scar, which is seen in over 60 % of FNH > 3 cm diameter. When present, the central scar enhances on the delayed images in more than 80 % of cases. FNH is a benign liver mass and thus treated conservatively. There is no risk of malignant transformation and a very low risk of bleeding.