S5861 Segmental Atrophy of the Liver: A Rare, Often Misdiagnosed Pseudotumor

Introduction: Segmental atrophy of the liver is a rare, often misdiagnosed pseudotumor that can lead to unnecessary surgical intervention. We describe a case of a 6ty-5-year-old man with an incidentally found hepatic mass with biopsy showing key histological features of segmental atrophy of the liver that guided conservative management. Case Description/Methods: A 65-year-old man with a history of hypertension, atrial fibrillation, and nephrolithiasis presented to the emergency department with acute, upper abdomen and left flank pain and blood in the urine. The patient does not smoke or drink. He has no family history of liver disease or cancer. Vitals, physical exam, complete blood count, and liver function tests were normal. A urinalysis showed blood. A computed tomography (CT) scan of the abdomen showed a 2 millimeter left mid-lumbar ureter stone with minimal hydronephrosis. Incidentally, a 5.9 centimeter solid lesion was noted in the right hepatic dome. The patient’s symptoms resolved with pain medications. He had a follow-up triphasic CT scan of the abdomen that showed a heterogeneous, exophytic, solid 5.7 centimeter mass in the posterior dome of the liver which was atypical for hemangioma. A targeted liver biopsy showed loss of hepatic parenchyma with marked elastotic to sclerotic stroma with intermixed abnormal blood vessels and mild inflammation, consistent with late stages of segmental atrophy. No malignancy was identified. Since the patient was asymptomatic, the patient is being followed conservatively. Discussion: Segmental atrophy of the liver is rare and often misdiagnosed due to the wide variability of histological changes. These include hepatic inflammation, loss of hepatic parenchyma, bile duct proliferation, biliary cysts, and elastotic and fibrotic changes. There are 3 stages based on the extent of elastosis/fibrosis. Early lesions have minimal elastosis. They are characterized by collapsed parenchyma. Advanced lesions have more elastosis. End-stage lesions appear as a fibrotic mass. Segmental atrophy of the liver is often misdiagnosed as sclerosing cavernous hemangioma, hydatid cyst, cirrhosis, hepatocellular carcinoma, and cholangiocarcinoma, frequently leading to surgery. This case highlights key histological features of segmental atrophy of the liver. Though malignancy is on the differential, we hope that this case raises awareness among clinicians for segmental atrophy of the liver as a probable diagnosis to help prevent unnecessary surgical intervention.