一位兩歲小孩於切除隱睪時發現睪丸周圍沾粘，睪丸變稍硬且表面粗燥。病理檢查發現隱睪內和隱睪外有許多不成熟之腎絲球和腎小管分佈於纖維間質，為中腎胚胎之遺留物。此種良性中腎胚胎遺留物可出現於胚胎性腺下移之路徑上，包括腎臟下極、腰荐背側、鼠蹊管、和副睪頭，但出現於睪丸之中腎胚胎遺留物則未曾於文獻記載。胚胎學上性腺和中腎於解剖位有極密切之關聯，可解釋此少見之異位中腎遺跡。中腎胚胎遺留物有時以腎外威氏瘤（extrarenal Wilms’tumor），腎外威氏瘤合併良性腎組織，增生異位性腎組織，或異位性腎組織合併腎芽成份(blastema components) 等方式出現。此病例之中腎胚胎遺留物為增生異位性腎組織，病人於手術後三年無局部復發。

A Two-year-old boy received simple orchidectomy for the left undescended testis. Two-thirds of the inguinal testis had been replaced by hyperplastic mesonephric remnants. Two satellite lesions, located one centimeter distal to the testis also revealed the same picture. This rare co-existence of intratesticular and extratesticular benign mesonephric remnants of an undescended testis may demonstrate the intimate anatomic relaltionships in early embryonal development.