Lobar atrophy of the liver

Hepatic segmental atrophy and nodular elastosis: imaging features

PURPOSE

To evaluate the imaging features of hepatic segmental atrophy and nodular elastosis.

MATERIALS AND METHODS

In this Institutional review board (IRB)-approved, HIPAA-compliant study, we reviewed imaging features in six cases of histologically confirmed hepatic segmental atrophy (HSA) and nodular elastosis (NE). Retrospective review of ultrasound (US) in 2 patients, computed tomography (CT) in 5 patients, magnetic resonance imaging (MRI) in 4 patients, and positron emission tomography (PET) in 2 patients was performed. Location, size, and attenuation/density/signal intensity of these lesions were evaluated. Clinical presentation and coexistent conditions were also recorded.

RESULTS

All six patients were females. Mean age of presentation was 58.3 years (range 37-80). A single HSA and NE lesion in each patient was found. The mean size of the lesion was 18 mm (range: 3 mm to 36 mm). Most lesions were detected incidentally (5/6). On contrast-enhanced single-phase (portal venous) CT, most lesions were hypodense (4/5) and one lesion was hyperdense to fatty liver parenchyma. On MRI, the lesions were iso- to hyperintense on T2-weighted images, T1 hypointense, and hyperintense on diffusion-weighted images (DWI). Three lesions were hypointense on arterial, portal venous, and delayed phases. One lesion occurring in fatty liver appeared hyperintense on all three phases. Gd-EOB-DTPA-enhanced images were available in 2 patients and lesions were hypointense on the 20-min hepatobiliary phase. On PET, two lesions were isometabolic to the background hepatic parenchyma. On ultrasound, one lesion appeared hypoechoic and another lesion isoechoic to hepatic parenchyma.

CONCLUSIONS

Hepatic segmental atrophy and nodular elastosis is an uncommon benign lesion and can simulate metastases due to variable imaging features. Lack of FDG uptake on PET/CT may be a clue to the benign nature of the lesion and may suggest the possibility of HSA and NE.

MRI rare finding: Absence of the left liver lobe

We report a rare case of left liver lobe absence in an 80-year-old male patient discovered during an MRI scan. The main imaging features of this condition are briefly reviewed, together with its pathogenesis and the most common associations and differential diagnoses.

Liver regeneration and the atrophy-hypertrophy complex

The atrophy-hypertrophy complex (AHC) refers to the controlled restoration of liver parenchyma following hepatocyte loss. Different types of injury (e.g., toxins, ischemia/reperfusion, biliary obstruction, and resection) elicit the same hypertrophic response in the remnant liver. The AHC involves complex anatomical, histological, cellular, and molecular processes. The signals responsible for these processes are both intrinsic and extrinsic to the liver and involve both physical and molecular events. In patients in whom resection of large liver malignancies would result in an inadequate functional liver remnant, preoperative portal vein embolization may increase the remnant liver sufficiently to permit aggressive resections. Through continued basic science research, the cellular mechanisms of the AHC may be maximized to permit curative resections in patients with potentially prohibitive liver function.

Lobar and segmental liver atrophy associated with hilar cholangiocarcinoma and the impact of hilar biliary anatomical variants: a pictorial essay

The radiological features of lobar and segmental liver atrophy and compensatory hypertrophy associated with biliary obstruction are important to recognise for diagnostic and therapeutic reasons. Atrophied lobes/segments reduce in volume and usually contain crowded dilated bile ducts extending close to the liver surface. There is often a “step” in the liver contour between the atrophied and non-atrophied parts. Hypertrophied right lobe or segments enlarge and show a prominently convex or “bulbous” visceral surface. The atrophied liver parenchyma may show lower attenuation on pre-contrast computed tomography (CT) and CT intravenous cholangiography (CT-IVC) and lower signal intensity on T1-weighted magnetic resonance imaging (MRI). Hilar biliary anatomical variants can have an impact on the patterns of lobar/segmental atrophy, as the cause of obstruction (e.g. cholangiocarcinoma) often commences in one branch, leading to atrophy in that drainage region before progressing to complete biliary obstruction and jaundice. Such variants are common and can result in unusual but explainable patterns of atrophy and hypertrophy. Examples of changes seen with and without hilar variants are presented that illustrate the radiological features of atrophy/hypertrophy.

Extreme left hepatic lobar atrophy in a case with hilar cholangiocarcinoma

We describe an unusual case of extreme hepatic left lobar atrophy with hilar cholangiocarcinoma. A 67-year-old woman was referred to Nippon Medical School with obstructive jaundice. On admission, computed tomography revealed dilated intrahepatic bile ducts and a defect in the area drained by the left side of the middle hepatic vein. A Spiegel lobe was demonstrated, but the left lobe could not be detected to the left side of the gallbladder. Percutaneous transhepatic cholangiography was performed and demonstrated obstruction of the intrahepatic bile duct at the hepatic hilum. A drainage catheter was left in place. Angiography revealed that the left hepatic artery was present, but there was narrowing of the left portal vein. A diagnosis of agenesis of the left hepatic lobe with hilar cholangiocarcinoma was made. At surgery, the left lobe appeared extremely atrophic without atrophy of the Spiegel lobe. The right anterior branches of the hepatic artery and portal vein had been invaded by carcinoma, so a left trisegmentectomy was performed. Final pathology was advanced hilar cholangiocarcinoma with invasion of the hepatic parenchyma, portal vein, and nervous system. The left lobe was atrophic without hepatolithiasis. The left portal vein was narrow distal to the Spiegel branch. The serum total bilirubin concentration was elevated postoperatively, and the patient was treated for hepatic failure. The patient died of pneumonia without recurrence 7 months after surgery. This rare case of extreme hepatic left lobar atrophy with hilar cholangiocarcinoma was successfully treated by left trisegmentectomy. Preoperative portal embolization was unnecessary because the left lobe was already atrophic.