A Case of Symptomatic Angiomyolipoma

Background: Renal angiomyolipoma (AML) are benign soft tissue neoplasms classically composed of blood vessels, smooth muscle cells and adipocytes. These masses are found in .3 to 2.1% of the population and can be strongly associated with genetic syndromes such as the Tuberous Sclerosis Complex. While most of these masses are found incidentally, they can, in rare cases, become symptomatic. Patients with symptomatic AML most commonly present with hematuria, flank pain and renal hemorrhage. Case Presentations: A.H. is a 51-year-old obese female who presented 7 months ago to the emergency department with sudden onset left upper quadrant pain, nausea and emesis. On admission, her hemoglobin was found to be 9.1. Due to continued anemia she was transfused with 2 units of blood. CT scan of the abdomen and pelvis showed massive hemorrhage in the retroperitoneum surrounding the left kidney and a focus of fatty tissue likely representing a large AML. After Urological consult, left renal pole artery embolization was performed by interventional radiology. Over the next several months, after resolution of the hemorrhage, subsequent scans found that the symptomatic mass measured 4 cm and another 1.2 cm AML was found in the ipsilateral kidney. 6 months’ post presentation it was determined that, due to size and history of hemorrhage that the patient would undergo a radical left nephrectomy. Upon surgical exploration of the abdomen the tissue around the kidney was found to still be incredibly inflamed and thick. Despite this, the surgery proceeded without complications. Conclusion: Classic AML are the only benign renal masses that can confidently be diagnosed using imaging. As such, confirmed asymptomatic AML are often left untreated and actively observed over time. The consensus in literature indicates a size 4 cm as the cutoff for when AML are suspicious for symptomatic manifestation. Indeed, the risk of significant symptoms directly increases with size of the mass. This same 4cm size cutoff is used as a guideline for when treatment is warranted. Modern first line treatment includes embolization, with partial or radical nephrectomy coming into play when embolization fails to control symptoms or with excessively large masses. In this case, although embolization initially controlled the bleeding, patient comorbidities and tumor size warranted definitive removal of the mass.