Epidermoid Cyst in the Kidney with Nephrolithiasis: A Case Report

ABSTRACT

Epidermoid cysts in the kidney have rarely been reported, and in most cases its pathogenesis has not been well understood. We report a case of an epidermoid cyst in a kidney with nephrolithiasis in a 61-year-old man. A pyelonephrolithotomy was performed on the patient four years ago to treat nephrolithiasis of the left kidney. During the follow-up, a newly developed mass was discovered three years ago and the mass has recently increased in size. A unilateral nephrectomy was performed under the clinical impression of renal cell carcinoma. Gross examination revealed a well encapsulated cystic mass measuring 3.0 x 2.0 x 2.0 cm and containing lumps of soft whitish material, in the upper pole of the left kidney. This location was the same as that of previous nephrolithiasis. Microscopic examination revealed typical findings of an epidermoid cyst. We suspect that the chronic irritation induced by renal stones may be associated with the development of the epidermoid cyst in this case.