Case of the Week

2021-08 / February 22

Contributors: Iryna V. Samarska and Jonathan I. Epstein

A man in his early 40s presented with an enlarged right testis.

Click on the below thumbnails to enlarge photos.

Quiz

1. What is the correct diagnosis?

a. Spermatocele

b. Simple cyst of the rete testis

c. Epidermoid cysts

d. Paratesticular serous cystadenoma

e. Papillary clear cell cystadenoma of the epididymis

The differential diagnosis of (para)testicular cystic lesions can be extensive and may include hydrocele, spermatocele, epidermoid cysts, tubular ectasia of the rete testis, sertoliform cystadenoma of the rete testis, well-differentiated papillary mesothelioma, paratesticular serous cystadenoma, and papillary clear cell cystadenoma of the epididymis.

A hydrocele is lined by a single layer of the mesothelium, which is positive for WT1 and other mesothelial markers. Well-differentiated papillary mesothelioma can be associated with hydrocele and contains (tubulo)papillary structures lined by mesothelium with minimal/mild cytonuclear atypia. Epidermoid cysts are lined by keratinizing squamous cell epithelium. Dermoid cysts show dermal adnexal structures in the cystic wall, lined by squamous epithelium. A spermatocele represents dilatation of an efferent ductule in the caput epididymis or the rete testis, lined by a single layer of epithelial cells, that can show cilia on the surface. Spermatoceles contain spermatozoa within the cyst fluid by the aspiration cytology. Tubular ectasia of the rete testis can be related to the obstruction and located in the mediastinum of the testis. Sertoliform cystadenoma of the rete testis is a well-circumscribed solid and cystic lesion mostly confined within dilated channels of the rete testis and consisting of tubules and cords/nests in the hyalinized or myxoid stroma. Papillary clear cell cystadenoma of the epididymis is a cystic lesion with intraluminal papillary projections lined by clear cells, associated with von Hippel-Lindau disease in one-third of the cases. Paratesticular serous cystadenoma belongs to the group of the ovarian-type lesions (Müllerian type tumors) of the testis and represents a cystic lesion lined by a cuboidal epithelium that is positive for PAX8, CK7, and CAIX. There should be no atypia or mitoses present. Papillary projections are occasionally observed but more often are absent. Müllerian tumors in this site are more often paratesticular but can also be seen intratesticular. The entire range of epithelial tumors identical to the surface epithelial-stromal tumors seen in the ovary can be seen, most commonly serous and mucinous benign, borderline, and malignant. Other less common ovarian-type tumors include those with Brenner, endometrioid, and clear cell differentiation.

1. Lin MS, Ayala AG, and Ro JY Ovarian-type tumors (Mullerian tumors) of the testis: Clinicopathologic findings with recent advances. Ann Urol Oncol 2019; 2(1): 36-45.

2. Cox R; Vang R; Epstein JI. Papillary Cystadenoma of the Epididymis and Broad Ligament. Am J Surg Pathol. 2014;38(5):713-8.

3. Paluru S; Ulbright T; Amin M; Montironi R; Epstein JI. The Morphologic Spectrum of Sertoliform Cystadenoma of the Rete Testis. Am J Surg Pathol. 2018;42(2):141-149.

About GUPS

The Genitourinary Pathology Society (GUPS) was formed with the vision of advancing the care of patients with urologic diseases through enhancements of best practices, research, and education in the subspecialty of Urological Pathology.

GUPS is an official Companion Society of the United States and Canadian Academy of Pathology (USCAP).

Contact

gupathologysociety@gmail.com

Powered by Wild Apricot Membership Software