Hepatic Mass in a 73-Year-Old Man

Abstract

Question: A 73-year-old man with history of hypertension and dyslipidemia was incidentally found to have a large liver mass on magnetic resonance imaging. He did not have a personal or family history of chronic liver disease, previously diagnosed malignancy, alcohol use, blood transfusion, or smoking. Physical examination revealed abdominal distention. A palpable mass and jaundice were absent. Comprehensive metabolic panel, complete blood count, alpha-fetoprotein, liver transaminases, and carcinoembryonic antigen were within reference range. Carbohydrate antigen 19-9 was elevated (45.8 U/mL). Serologic studies for hepatitis B surface antigen and hepatitis C core antigen were negative. Antibody to hepatitis B surface antigen was positive. Computed tomography (CT) was performed, revealing a large right hepatic lobe mass, >20 cm in greatest dimension (Figure A). The mass had predominantly fatty attenuation with interspersed wispy soft tissue attenuation, multiple scattered small round enhancing nodules, and prominent dilated irregular enhancing vessels. A right lobectomy was performed. Pathologic examination of the 3503.6-g resection specimen revealed a 22 cm, well-circumscribed yet unencapsulated yellow-tan variegated soft mass with hemorrhagic foci (Figure B). The uninvolved hepatic parenchyma was grossly unremarkable. Histologically, the mass consisted of a mixture of smooth muscle cells (arrows), abnormal thick-walled blood vessels, mature adipose tissue, and foci of hematopoietic elements (Figure C). The smooth muscle cells were positive for the melanocytic lineage marker homatropine methylbromide 45 (HMB-45) (Figure D). What is the diagnosis? Look on page 679 for the answer and see the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. These findings are consistent with those of an angiomyolipoma (AML). On CT, AMLs are heterogeneously hypodense masses with dilated central vessels. Radiologic variability between cases owing to the amount of each of the 3 tumor elements is high. Gross pathology shows a circumscribed, unencapsulated mass with variegation in color. Histologically, the tumor is composed of adipocytes, thick irregular vessels, and smooth muscle cells with cytoplasmic immunoreactivity for HMB-45. Hematopoietic foci (Figure C, asterisk) are often present. AML is a rare, benign member of the PEComa, or perivascular epithelioid cell tumor, family of neoplasms. The liver is only second to the kidney as the most common site, although <300 cases of hepatic AML have been reported. Unlike renal AMLs, only 6% of hepatic AMLs are associated with tuberous sclerosis. Hepatic AML is approximately 4 times as common in females with mean age of diagnosis in the fifth decade. The majority of hepatic AMLs are <10 cm in greatest dimension1Zeng J.P. Dong J.H. Zhang W.Z. et al.Hepatic angiomyolipoma: a clinical experience in diagnosis and treatment.Dig Dis Sci. 2010; 55: 3235-3240Crossref PubMed Scopus (37) Google Scholar and can be managed conservatively. Radiologic diagnosis can be challenging because of the quantitative variation in each of the 3 elements of the tumor. The differential diagnosis includes hepatocellular carcinoma in hypervascular AMLs as well as liposarcoma in fatty AMLs. CT and magnetic resonance imaging are the preferred diagnostic imaging modalities. Zeng et al1Zeng J.P. Dong J.H. Zhang W.Z. et al.Hepatic angiomyolipoma: a clinical experience in diagnosis and treatment.Dig Dis Sci. 2010; 55: 3235-3240Crossref PubMed Scopus (37) Google Scholar reported a correct preoperative diagnosis of only 18%, with 60% of cases mistaken for hepatocellular carcinoma. Although hepatic AML is most frequently a benign tumor, life-threatening complications include malignant transformation2Nguyen T.T. Gorman B. Shields D. et al.Malignant hepatic angiomyolipoma: report of a case and review of literature.Am J Surg Pathol. 2008; 32: 793-798Crossref PubMed Scopus (87) Google Scholar and spontaneous rupture.3Guidi G. Catalano O. Rotondo A. Spontaneous rupture of a hepatic angiomyolipoma: CT findings and literature review.EurRadiol. 1997; 7: 335-337Google Scholar