Ejaculatory duct cyst - Cowper duct syringocele - Arnold Chiari malformation

Case contributed by Ammar Haouimi
Diagnosis probable


Known case of Arnold-Chiari malformation (not operated) with recurrent discharge from a fistulous orifice at the base of the penis. An MRI of the perineum was requested.

Patient Data

Age: 4 years
Gender: Male

Trabeculated urinary bladder with reduced capacity and increased longitudinal axis (neurogenic bladder). There is dilatation of the posterior urethra with a small ejaculatory duct cyst.

A large cystic lesion is seen at the base of the penis below the level of the bulbourethral glands  (Cowper glands) of low signal intensity on T1, and high intensity on T2 with a thin peripheral rim of enhancement. This likely represents a Cowper duct syringocele. This cystic lesion shows a localized posterior triangular shape pointing toward the presumed cutaneous fistulous orifice (fistulous tract). Another fistulous tract is seen extending from this collection to the posterior urethra which may indicate a perforated syringocele.


The sagittal T2 sequence demonstrates myelomeningocele with a tethered cord (Known case of Arnold-Chiari malformation).

Case Discussion

MRI features of possible large Cowper duct syringocele with ejaculatory duct cyst in patient Arnold-Chiari malformation (or Chiari II malformation).

The analysis of the fluid from the cutaneous fistulous orifice showed a composition identical to that of the urine, indicating most likely Cowper duct syringocele - posterior urethra fistula. The VCUG was not requested by the pediatric surgeon.

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