• Dilatation of the efferent ductules in the rete testis or head of epididymis

• All ages affected, but typically occur in 20 - 50 year old men

• Usually idiopathic but obstruction of outflow may play a role

• Painless bulging

• By ultrasound, cyst contents in uncomplicated cases are well defined, anechoic, with no internal echoes
• Cyst may displace the testis if it is large
• This is distinct from hydrocele, which envelops the testis but does not displace it

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• Arrives in laboratory as a collapsed membrane

• Lined by single layer of cuboid to flat epithelium which is often ciliated
• Thin wall of fibromuscular soft tissue
• Cysts may be unilocular or multilocular; translucent
• Lumen contains spermatozoa and proteinaceous fluid
• Associated with foreign body giant cell reaction, cholesterol clefts
• Epithelial lining may form a benign papilloma with fibromuscular cores lined by a single layer of columnar to cuboid epithelium with vacuolated cytoplasm

Contributed by Kenneth Iczkowski, M.D.

• Cytokeratins

• Calretinin

• J Urol 2014;192:1179, Case Rep Urol 2015;2015:731987

Spermatocele:


1. Has a lining of mesothelial cells
2. Is cytokeratin negative
3. May have papillary infoldings with fibrovascular cores lined by vacuolated cuboidal or columnar cells
4. Originates from the same membrane as hydrocele

C. May have papillary infoldings with fibrovascular cores lined by vacuolated cuboidal or columnar cells.

A. The lining is epithelial, not mesothelial.
B. Spermatocele is cytokeratin positive, unlike hydrocele.
D. Origin of spermatocele is from rete testis / head of epididymis epithelium, whereas hydrocele originates from the mesothelium of the tunica vaginalis.