Testis & paratestis

• Includes true cysts and fluid collections (celes) of the spermatic cord and paratesticular structures
• 2 main types
  • Extratesticular (arises from the mesothelial lining [tunica vaginalis] and does not communicate with tubular system)
    • Hydrocele
      • Encysted presentation does not communicate with peritoneal cavity
      • Funicular presentation does communicate with peritoneal cavity
    • Mesothelial cyst (also termed spermatic cord cyst)
  • Testicular (arises from the epithelial lining of the rete testis, efferent ducts and epididymis)
    • Epididymal cysts and cystic dilatation (tubular ectasia) of epididymis and rete testis are associated and likely exist on a continuum
    • Epididymal cysts > 2 cm within the vaginal cavity are termed spermatocele
    • Cystic dysplasia of rete testis is distinctive congenital malformation

• ICD-10:
  • N50.3 - cyst of epididymis
  • N50.89 - other specified disorders of the male genital organs
  • N50.81 - testicular pain
    • N50.811 - right testicular pain
    • N50.812 - left testicular pain
    • N50.819 - testicular pain, unspecified
  • N50.82 - scrotal pain
  • N50.9 - disorder of male genital organs, unspecified

• Hydrocele
  • Congenital form occurs due to patent processus vaginalis or abnormal closure of processus; most regress by adulthood
  • May be associated with trauma, testicular torsion, tumors, chronic inflammation (e.g., in setting of bacterial epidiymoorchitis, filarial disease) or congenital lymphatic malformations
• Mesothelial cyst
  • Mesothelial rests trapped during embryonic development (J Urol 1975;114:730)
• Cysts (and cystic dilatation) of epididymis and rete testis
  • Acquired condition frequently associated with or resulting from mechanical compression of epididymis or spermatic cord by surgical changes (e.g., vasectomy), trauma, neoplastic or infectious process, dialysis (rete testis cystic dilation) or hormonally induced atrophy of epididymis (e.g., secondary to cirrhosis) (Hum Pathol 1996;27:336, Am J Surg Pathol 1996;20:1231, J Ultrasound 2011;14:208)
  • Rare intraparenchymal cystic dilatation of seminiferous tubules may result from focal malformation or inflammation
  • Epididymal cysts associated with in utero exposure to diethylstilbestrol
• Cystic dysplasia of rete testis
  • Congenital malformation of rete testis, frequently associated with ipsilateral urogenital malformations (e.g., renal agenesis, multicystic dysplasia of the kidney)
  • Thought to arise due to disorders of communication between mesonephric duct and germinal epithelium during development (Front Pediatr 2022;10:898038)

• Transillumination
• Ultrasonography (Doppler ultrasonography is important in a setting of painful swelling to rule out testicular torsion)

• Varies by entity
• Most frequently characterized by simple uninoculated or multiloculated fluid filled cystic structures
• Complex loculations or areas of solid growth should raise concern for alternative etiology

Images hosted on other servers:

AFIP images


Images hosted on other servers:

Contributed by Stephanie Siegmund, M.D., Ph.D. and AFIP

• Right testes:
  • Mesothelium lined cyst (3.0 cm), consistent with hydrocele sac

• Spermatocele sac:
  • Ciliated columnar / cuboidal cell lined cyst with aggregates of spermatozoa, consistent with spermatocele

A 67 year old patient with a history of cirrhosis presents with painless scrotal swelling. An orchiectomy reveals the paratesticular lesion pictured above. What is the most likely diagnosis?

1. Cystic dilatation of epididymis
2. Hydrocele
3. Mesothelial cyst
4. Spermatocele
5. Teratoma

A. Cystic dilation of epididymis. The image shows a cystically dilated epididymis with proteinaceous luminal accumulation in a cystic space lined by tubal epithelium. Answer E is incorrect because the structure is consistent with normal histology in this location rather than teratomatous elements and teratoma would be less common in an elderly patient with a history of hormonal abnormality (i.e., cirrhosis). Answers C and B are incorrect because a mesothelial cyst or hydrocele would be lined by mesothelium. Answer D is incorrect because while spermatocele is also an epididymal structure lined by tubal epithelium, there is no evidence of spermatozoa in this image.

Comment Here

Reference: Cysts

Which of the following clinical scenarios is most likely to be associated with cystic dysplasia of the rete testis?

1. 4 day old neonate with persistent bilateral scrotal swelling
2. 5 year old boy with a complex solid and cystic scrotal mass
3. 6 year old boy with right renal agenesis and unilateral scrotal swelling
4. 34 year old man with 2 months of painful unilateral scrotal mass and recent diagnosis of tuberculosis
5. 67 year old man with metastatic castration resistant prostatic adenocarcinoma

C. 6 year old boy with right renal agenesis and unilateral scrotal swelling. Cystic dysplasia of the rete testis is most commonly seen in children (median age is 5 years old) and is frequently associated with ipsilateral urogenital malformations, such as renal agenesis. Answer A is incorrect because by contrast, unilateral or bilateral neonatal scrotal swelling is most commonly due to persistent patency of the processus vaginalis with spontaneous resolution by 1 - 2 years of age. Answers E and D are incorrect because scrotal swelling in adults is more frequently due to cysts or cystic dilatation of the epididymis or rete testis secondary to obstruction in the setting of hormonal changes, neoplastic processes, surgery or infection. Answer B is incorrect because the presence of a complex scrotal mass rather than uniloculated or multiloculated fluid filled mass raises the possibility of prepubertal teratoma.

Comment Here

Reference: Cysts