Wünderlich syndrome following rupture of an Angiomyolipoma

Clinical History

A 69-year-old woman presents to the emergency room with an intense pain located at the right hemiabdomen, refractory to endovenous analgesia. Laboratory tests reveal a leukocyte count of 14.000 and left shift. The patient presents no fever and displays no abdominal guarding. Medical history included cholecystectomy and appendectomy.

Imaging Findings

CT shows two small hypoattenuating renal lesions, one in each side compatible with angiomyolipomas. Subcapsular and perinephric haemorrhages are depicted on the right kidney.

Discussion

Angiomyolipomas (AMLs) are uncommon benign renal tumours composed of varying amounts of fat, smooth muscle and abnormal thick-walled blood vessels. A minority (4.5%) of these tumours are classified as minimal fat AMLs as they contain only microscopically detectable fat [1]. They may present isolated or associated with tuberous sclerosis. Isolated or sporadic AMLs represent the vast majority of cases (80-90%), are usually unilateral or focal and tend to occur in women aged 40-70. AMLs associated with tuberous sclerosis are usually bilateral and multifocal and occur at any age in either sex. The tumour is often incidentally detected during a US or CT exam as most patients are asymptomatic [2].

When symptomatic, common clinical manifestations are flank or abdominal pain, palpable mass and hematuria related to spontaneous intramural or extramural hemorrhage. Hemorrhage (its main complication) is related to tumour size, increased vascularity and abnormal thick-walled vessels that predispose to microaneurysms and bleeding formation. Tumours larger than 4 cms are considered to be at high risk for bleeding [3].

At US exam, AMLs appear as a marked hyperechoic mass due to high fat content and multiple tissue interfaces produced by fat and multiple vessels [2]. This feature is however not pathognomonic at all. A myriad of other tumours including renal cell carcinoma, liposarcoma, atypical Wilms' tumour, lymphoma, lipoma, oncocytoma and cavernous hemangioma can manifest as hyperechoic. Diagnostic is often confirmed with a CT exam demonstrating the presence of fatty tissue, a highly specific feature [2]. Noteworthy is the fact that AML rarely contain calcifications, a finding that would render its diagnosis not feasible [4]. Some AMLs contain predominantly muscle and blood vessels with scanty fat component and its imaging differentiation from renal cell carcinoma is extremely hard to establish.

MRI will most reliably demonstrate the bulk fat within a renal angiomyolipoma by comparing images obtained with the same imaging parameters before and after fat-suppression techniques. The appearance of angiomyolipoma on T2-weighted images is variable and depends on the volume of fat tissue within the lesion [5-7].

AMLs' treatment depends on its size. An isolated AML less than 4 cm will only require a conservative follow-up with either US or CT. If the lesion is larger than 4 cm and bleeding or uncontrollable pain is present renal sparing surgery or renal arterial embolisation should be performed. The minimally invasive treatment by selective arterial embolisation should be preferred in order to spare nephrons [8].

Differential Diagnosis List

Final Diagnosis

Wünderlich syndrome following rupture of an Angiomyolipoma

URL:	https://www.eurorad.org/case/14026
DOI:	10.1594/EURORAD/CASE.14026
ISSN:	1563-4086