Retroperitoneal Angiomyolipoma: A Case Report and Review of the Literature

Retroperitoneal angiomyolipoma is a rare tumour that is difficult to diagnose preoperatively. We present a case of retroperitoneal angiomyolipoma that highlights its diagnostic dilemma. We also performed a literature review and present a review of retroperitoneal angiomyolipoma. 1. Introduction Angiomyolipomas (AMLs) are composed of three tissue elements: mature adipose tissue, thick walled blood vessels, and smooth muscle cells. AMLs were originally classified as hamartomas but are now thought to belong to the family of perivascular epithelioid cell tumours (PEComas) [1]. AMLs are most commonly found in the kidney, and although most of them are sporadic, 20% are associated with tuberous sclerosis [2]. Rare cases of extrarenal AML have been reported affecting most commonly the liver and uterus, but to some extent the vagina, fallopian tubes, penis, lung, colon, nasal cavity, abdominal wall, and retroperitoneum [3]. Renal AMLs are present in 0.13% of the population [4] with only eleven retroperitoneal AMLs reported in the English literature [5]. Retroperitoneal AML patients present with abdominal pain, increasing abdominal girth, as incidental findings on imaging studies, or with spontaneous rupture [6]. Ultrasound and CT scan can correctly diagnose renal AML in 86% of cases [4]. Extrarenal AMLs, however, are more difficult to diagnose on imaging as they often lack fat densities [7]. Most cases of retroperitoneal AML have been treated with surgical excision, but successful conservative renal sparing management with angiographic embolisation has been reported in one case [8]. AMLs greater than 4？cm in size are more likely to be symptomatic and warrant intervention [9]. We present a case and review the literature to give an up-to-date perspective on retroperitoneal AML. 2. Case Report A 71-year-old man was referred from his general practitioner with hematochezia. He had no medical conditions; specifically, he did not have tuberous sclerosis but had a family history of a brother who died from colorectal cancer at the age of 60. Physical examination including digital rectal examination revealed a rectal mass. He had a significantly raised CEA (19.1？ug/L—RR < 5.0) and a slightly raised CA19-9 (35？U/mL—RR < 34) and went on to have a colonoscopy that showed a rectal mass with carcinoma confirmed on histological biopsy. Staging CT scan, as seen in Figure 1, showed thickening of the rectal wall but also revealed a large (9 × 9 × 10？cm) right sided retroperitoneal mass. The mass was heterogeneous with some calcification internally and peripherally with a smooth