Common and epithelioid variants of hepatic angiomyolipoma exhibit clonal growth and share a distinctive immunophenotype

Abstract

In contrast to the common renal angiomyolipoma (AML), 1 AML of the liver is very rare and has been recognized only since 1976. 2 Liver AML are usually unifocal tumors without the background of tuberous sclerosis (TSC). Until recently, AML was generally thought to be a hamartoma, composed of several tissue components. Renal AML have already been proven to be monoclonal neoplasms. 3,4 Loss of heterozygosity in the region of the tuberous sclerosis genes TSC1 (9q24) or TSC2 (16p13.3) has been shown in AML and several other "hamartomas" of TSC patients. 5,6 Malignant AML of the kidney have been described in exceptional cases. 7,8 AML of the liver displays a considerable morphologic heterogeneity. The epithelioid variant closely resembles liver cell adenomas. To find out whether a different phenotype reflects a different nature of a hamartoma or a true neoplasm, we analyzed clonality within a series of hepatic AML in female patients using the human androgen receptor (HUMARA) gene. 9 Furthermore, a broad panel of monoclonal antibodies was applied to assess heterogeneity and find useful markers in diagnostically puzzling cases, particularly the recently described monophasic epithelioid variant. MATERIALS AND METHODSAML samples were derived from archival tissue from the Institute of Pathology, Hannover Medical School. Tumor tissue had been fixed in neutral buffered formalin and embedded in paraffin. The material available ranged from 1 (needle biopsies) to 20 paraffin blocks. Slides only were maintained from 2 patients. A series of 17 antibodies was applied for immunohistochemical analysis on serial sections of 5 m thickness using the alkaline-phosphatase-anti-alkaline-phosphatase method after microwave antigen retrieval as described. 10 The extent of staining was graded on a scale from faint to moderate to strong.DNA Extraction. Formalin-fixed, paraffin-embedded tissues were serially sectioned at 15 m and mounted on glass slides. Tumor and normal liver were selectively sampled by microdissection. DNA was extracted by overnight digestion at 56°C with proteinase K followed by extensive organic extraction and ethanol precipitation. Approximately 100 ng genomic DNA was incubated overnight with 10 units HpaII according to the manufacturer's instructions (MBI Fermentas, St. Leon-Rot, Germany). As a negative control, DNA was incubated with restriction buffer only. After digestion samples were incubated for 15 minutes at 65°C to inactivate the restriction enzyme.Assessment of Clonality. Clonality at the HUMARA locus was assessed by polymerase chain reaction (PCR) essentially as described. 11 One tenth of the restriction digest was amplified using 2.5 pmol each of the primers AR-C sense and AR-C antisense in a total volume of 25 L for 40 cycles in the presence of 3 mmol/L MgCl 2 , 200 mmol/L dNTP, and 0.25 units RedTaq-Polymerase (Sigma, Deisenhofen, Germany). The sense primer was fluorescence-labeled (IRD-700; MWG BioTech, Ebersberg, Germany) and the PCR products were separated and detected in a 6% denaturing polyacrylamide ge...

Correlation of MRI and CT findings with histopathology in hepatic angiomyolipoma

“…Immunohistochemistry (Fig. 4) was consistent with marker profiles established in previous studies and allowed the definitive diagnosis of AML [13,14].…”

“…Immunohistochemistry was performed on serial sections with several different antibodies using the alkaline-phosphatase-anti-alkalinephosphatase (APAAP) method. In agreement with marker profiles of other studies, the diagnosis was based on the positive staining of AML with the melanocytic markers HMB-45 (Dako, Denmark) and CD 63(NKI-C-3; Enzo, USA) [13,14,15], as well as the negative staining with the pankeratin markers KL 1 (Immunotech, France) and AE1/AE3 (Dako, Denmark) [13,15]. Kl-67 (MIB-1; Novocastra, UK), a marker of the proliferative activity, ranged from < 1 to 3 % in patients 2±5 and 7 and was increased to 5 % in patient 6 [13].…”

“…The AML in patient 5 was oval shaped with a smooth margin, homogeneous, and hypovascular. On the other hand, the AML in patient 6 showed signs of a low malignant potential [13]. The recurrent tumor was unusual in terms of its multinodular appearance, its arteriovenous shunts, its less-defined border on histology, and its high proliferative activity.…”

“…Only very recently the first malignant transformations of two hepatic AMLs were found [13,15], and it has been concluded that monophasic-epithelioid AML of the liver should be considered a neoplasia with a low malignant potential. However, the mortality and morbidity associated with partial hepatectomy is by no means negligible, and since AMLs are in general benign tumors, conservative clinical management is justified.…”

Angiomyolipoma of the Liver with Systemic Inflammatory Response and Intratumoral Hemorrhage

“…, Yasuni Nakanuma 2) , Yusuke Kinugasa 3) , Etsuro Bando Division of Gastroenterological Surgery, Shizuoka Cancer Center Hospital…”