Imaging Features of Renal Capsule Leiomyoma on Contrast-Enhanced Ultrasonography: A Case Report

Abstract

Leiomyomas of the kidney are rare, mostly occurring in adults as incidental findings, and are a diagnostic challenge. In a renal transplant recipient population, an increased risk of tumors is observed due to the effect of immunosuppressive drugs. A differential diagnosis between leiomyomas and other malignant lesions is not possible with current imaging methods. This report presents a case of a native kidney capsular leiomyoma in a kidney transplant recipient and highlights the features of computed tomography and contrast-enhanced ultrasound (CEUS), along with the histopathologic analysis. The CEUS and quantification studies are helpful in demonstrating the vascularization pattern of the renal capsular leiomyoma. This entity appearing with chronic kidney disease can resemble a renal cell carcinoma, in an otherwise healthy kidney. In this case, CEUS was useful for diagnosing the vascularization of the renal mass, although the pattern of intense vascularization could be diagnostically misleading, implying a malignant lesion. However, the pattern of enhancement due to CEUS showed no peculiarities that indicated histopathologic diagnosis.