Microlithiasis of the epididymis and the rete testis

Testicular microlithiasis is a well-defined clinical and pathologic entity easily diagnosed through testicular echography; however, its association with cancer and infertility is now under debate. Many efforts have been done in recent years to clarify the spectrum of lesions observed in testicular microlithiasis, but no published data as to the existence of a possible microlithiasis of the epididymis and the rete testis have been found. We have observed microlithiasis of the epididymis and the rete testis in surgical (8 epididymis and 6 testis) and autopsy specimens (12 cases). In decreased order of frequency, microliths of the proximal spermatic way were seen in rete testis, epididymal duct, and efferent ducts. Intraluminal, subepithelial, and interstitial microliths were localized along these segments of the spermatic way. Subepithelial microliths were the most frequently found. A granulomatous reaction around the interstitial epididymal microliths, mimicking malacoplakia, was observed in 1 case. The differential diagnosis of microliths includes corpora amilacea, Michaelis-Gutmann bodies, calcium deposits, hyaline globules, and parasites, like the giant kidney worm Dioctophyme renale. In infants and young adults, microlithiasis of the epididymis and the rete testis is frequently associated with alterations in the development of the proximal spermatic way. In elderly adults, it is related to ischemia and obstruction of the spermatic way.