Hepatic epithelioid angiomyolipoma with renal metastasis: radiologic-pathologic correlation

Abstract

Epithelioid angiomyolipoma (EAML) is a rare subtype of angiomyolipomas. Unlike the conventional angiomyolipomas, EAML often contains minimal fat which usually precludes prospective diagnosis on imaging. The imaging findings of EAML may overlap with other benign and malignant hepatic neoplasms. We report a hepatic epithelioid angiomyolipoma in a 47-year-old female which metastasized to the right kidney and recurred after resection in the liver. We analyze the imaging findings of EAML on ultrasound, computed tomography, positron emission tomography and magnetic resonance imaging. Correlation between the imaging and histopathologic findings is made. The estimated annual growth and doubling time of the primary hepatic EAML are calculated. To the best of our knowledge, this is the first published report of positron emission tomography-computed tomography findings and annual growth rate for hepatic EAML.

Keywords: Epithelioid angiomyolipoma; Liver PET.

Fig. 1

First computed tomography examination during the initial presentation (patient age 47 years): the primary lesion in the right hepatic lobe which is slightly hypoattenuating to the remainder of the liver parenchyma (M) on the nonenhanced computed tomography (a). It demonstrates heterogeneous avid enhancement on the arterial phase (b). Note the linear intralesional structures which represent prominent vessels centrally in the lesion and at the periphery (arrows in b). On the portal venous phase, the mass demonstrates mild washout, best seen in the right lateral part (arrows in c). Pseudocapsule is seen on the delayed phase (arrows in d) while the mass demonstrates mild washout (d). Incidental note is made of multiple hyperdense gallbladder stones (short arrow in a).

Fig. 2

The follow-up portal venous phase computed tomography performed 6 years and 4 months after the initial presentation (patient age 53 years) (a and b); showing significant interval growth of the right hepatic lobe mass (M in a) and a new development of an interpolar partially exophytic right renal mass (M in b). The previous arterial phase computed tomography during the initial presentation at the same level of (b), is provided for comparison (c).

Fig. 3

The ultrasound image with Doppler Interrogation (7 years after the initial presentation, patient age 55 years): showing a large relatively hyperechoic partially exophytic right hepatic lobe mass with internal vascularity. Note the dilated vessels within the mass (thick arrows).

Fig. 4

Fused fluorodeoxyglucose positron emission tomography–computed tomography images (7 years after the initial presentation, patient age 54 years) showing similar fluorodeoxyglucose uptake of the right hepatic lobe epithelioid angiomyolipoma (M in a) to the remainder of the liver parenchyma (L in a). The renal epithelioid angiomyolipoma, however, demonstrates more avid uptake in comparison to both the renal parenchyma and the hepatic mass (renal mass (RM) in d).

Fig. 5

Nonenhanced magnetic resonance imaging of the liver (8 years after the initial presentation, patient age 55 years) showing the large hepatic epithelioid angiomyolipoma which demonstrates hypointense signal on T1-WI (M in a), heterogeneous signal on T2-WI (M in b) and hyperintense signal on the diffusion weighted imaging (DWI) (M in c). Note the linear flow void vessels in the T2-WI and DWI (arrows in b and c). T2-WI with fat saturation, at the level of the right renal mass which demonstrates heterogeneous signal on T2-WI but predominantly hyperintense (RM in d).

Fig. 6

The formula and the values used to calculate the tumor growth rate of the right hepatic lobe epithelioid angiomyolipoma. (SGR, specific growth rate; t, time; ln, natural log; V, tumor volume in centimeter cube).