A case of pararenal angiomyolipoma arising from an existing exophytic angiomyolipoma

Abstract

A 52-year-old healthy woman with a congenital solitary right kidney presented with an incidentally found pararenal mass. Computed tomography and magnetic resonance imaging revealed an exophytic mass in the right kidney consistent with an angiomyolipoma and an additional enhancing pararenal mass that contained fatty elements. Differential diagnosis of the mass included liposarcoma and angiomyolipoma. Upon exploration, the exophytic angiomyolipoma was found to be contiguous with the pararenal mass via an isthmus of fatty tissue. Frozen sections were taken from both masses which confirmed that both were angiomyolipoma. This is the first case reported in the literature wherein an angiomyolipoma extended extrarenally and formed a significantly larger pararenal mass. Can Urol Assoc J 2010;4(3):E79-E81 IntroductionAngiomyolipoma (AML) is a benign tumour composed of fat, muscle and blood vessels. These tumours generally present within the kidneys, but there are reports in the literature of extrarenal AML, most commonly occurring in the liver and uterus. 1 Few reports have described an extrarenal extension of an AML.Two different types of AMLs have been described: fatpoor and classic. Fat-poor AML have been shown to evade radiographic diagnosis because of their lack of lipid component.2 While classic AML demonstrate all three components on histology, in certain cases one of the three constituents may dominate. Of note are the epithelial cell dominated AMLs, which are a more aggressive subtype that have the potential to metastasize.3 Some cases of AML can often be difficult to distinguish from liposarcoma, 4 as both types of tumours have fatty components. We report a case of a suspected angiomyolipoma in which a suspicious extrarenal extension of the mass prompted further investigation. Case reportA 52-year-old woman, with a history of microhematuria, was referred for evaluation of two suspicious renal masses on the right side. Past medical history was significant for a congenital solitary kidney. The patient had no other complaints and abdominal exam was benign. The results of laboratory studies including biochemistry and differential blood cell count were within normal limits. Abdominal computed tomography (CT) scan revealed a right renal mass and a right pararenal mass (Fig. 1a) (Fig. 1b). Magnetic resonance imaging studies confirmed that the pararenal mass enhanced with administration of contrast and also contained fatty elements (Fig. 2). The small exophytic renal mass was consistent with AML (Fig. 1b). The larger pararenal mass was more concerning; based on radiologic imaging it was difficult to determine whether the mass was a liposarcoma, which would require excision, or an AML which could simply be observed. It could not be determined whether the pararenal mass was in any way related to the exophytic AML.A CT-guided biopsy was considered but declined because of the significant risk of bleeding and also due to the potential for inconclusive diagnosis on fine needle aspiration. Also, due to the heightened c...

Tumor necrosis after preventive embolization of large renal angiomyolipomas

“…In most cases, AMLs show tissue heterogeneity (vascular, adipose and muscle tissue) [1][2][3][4][5][6][7]. This category of lesion is rare, representing 1% of renal tumors, with an incidence ranging from 0.07 to 0.3% [8,9].…”

Nécrose tumorale après embolisation préventive des volumineux angiomyolipomes du rein

“…Cette lésion reste rare [8] et constitue 1 % des tumeurs rénales avec une incidence de 0,07 à 0,3 % [9].…”