Angiomyolipoma of the liver: Its clinical and pathological diversity

Abstract

Eighty cases (82 tumors) of hepatic angiomyolipoma (AML) from the world literature were reviewed, including our 8 cases. The tumors occurred predominantly in females (female:male ratio, 56:24). Only six patients (7.5 %) had associated tuberous sclerosis. The majority of the tumors (95%) occurred in non-cirrhotic, almost normal liver. The tumors usually presented as a hyperechoic mass on ultrasound (US) examination, a hypodense mass on computed tomography (CT) scan, and hyperintense mass on both T1-and T2-weighted magnetic resonance (MR) imagings. However, the imaging features of the tumor were occasionally variable according to the content of fat tissue component, and the tumors could not be clearly differentiated from other hepatic tumors, particularly hepatocellular carcinoma (HCC), based on the imaging features alone. Tumor location was recorded in 81 tumors; 44 were located in the right lobe, 30 in the left, 5 in the caudate, and 2 in both lobes of the liver. The tumor diameter ranged from 0.3 to 36 cm (mean, 8.0 + 7.0cm). Macroscopically, the tumors usually had no fibrous capsule. The cut surface was yellow to dark brown depending on the amount of fat tissue or blood vessels. The histologic features were quite variable and occasionally included atypical and/or pleomorphic cells, which could lead to the erroneous diagnosis of a variety of benign and malignant tumors, including lipoma, leiomyoma, HCC, hepatoblastoma, leiomyosarcoma, and malignant fibrous histiocytoma. Extramedullary hematopoiesis was found in 33% of the tumors. Reactivity of the tumor cells of the liver with HMB-45, a melanoma-specific antibody, can accurately establish the diagnosis of AML.

Angiomyolipoma of the liver: a reappraisal of morphological features and delineation of new characteristic histological features from the clinicopathological findings of 55 tumours in 47 patients

“…Eight resected tumours from seven patients were retrieved from the tissue registry files at the Pathology Section of Kanazawa University Hospital and related hospitals; six tumours from six patients were collected from the files of the Pathology Section of Nara Medical University Hospital and its related hospitals; and the remaining 41 tumours from 34 patients were collected from various hospitals in Japan. Nine surgically resected cases and two autopsy cases have been reported previously 6,8–15 . In the surgical cases, the entire tumour was submitted for histological examination.…”

“…Hepatic AMLs are composed of three heterogeneous tissue components – blood vessels, smooth muscle cells (SMCs), and fat cells – with proportions varying from case to case and from area to area within the same tumour. This results in a broad histological spectrum of appearances, ranging from benign lipomatous, leiomyomatous or angiomatous tumours at one extreme to bizarre pleomorphic epithelioid cell tumours at the other, 7,8 although we have not experienced a case classified as angiomatous AML so far. This histological diversity results in a wide range of imaging findings with modalities such as ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), and makes it difficult to differentiate AML from other primary benign and malignant hepatic neoplasms, especially hepatocellular carcinoma (HCC).…”

“…Furthermore, the SMC element often shows atypical and pleomorphic features, in terms of both cell morphology and growth pattern 5,6,9 . Thus, hepatic AMLs may mimic malignant neoplasms, and have been frequently confused with other tumours such as HCC, hepatoblastoma and malignant fibrous histiocytoma 5–9 . However, the histological features and growth patterns of hepatic AML have not yet been well elucidated.…”

Angiomyolipoma of the liver

“…With recent advances in diagnostic modalities, including ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and ®ne-needle aspiration biopsy (FNAB), reports of the tumor have been increasing. To date, only approximately 80 cases have been reported in the English literature [4]. During the past 12 years, we have encountered eight cases of hepatic angiomyolipoma, and, here, we provided data on these eight cases regarding clinical presentations, diagnosis, and management.…”

Angiomyolipoma of the liver: Case report and collective review of cases diagnosed from fine needle aspiration biopsy specimens

“…The first case was reported by Ishak in 1976 1. Nonomura et al2 reported 80 cases in 1996, and since their report, an additional 5 cases have been reported in the literature according to our search of MEDLINE 3,4. Histologically, the tumor is characterized by an admixture of mature fat cells, blood vessels, and smooth muscle cells, although the proportions of the various components may vary considerably in different parts of individual…”