Therapeutic role of ultrasound guided fine needle aspiration of prostatic parenchymal cysts

Background: Prostatic cysts may be classified as cysts associated with hyperplasia, prostatic retention cysts and cysts associated with squamous metaplasia (Comp Cont Ed Pract Vet 1995, 17: 791-810). Fine needle aspiration under ultrasonographic guidance is a safe method for diagnosis of parenchymal prostatic cysts (J Small Anim Pract 1995:36 105-113). Castration is considered the most effective treatment for intraprostatic cysts; rarely surgical drainage with excision or marsupialization is needed. Aim: To evaluate the curative rate of ultrasound guided fine needle aspiration of prostatic parenchymal cysts in the dog. Method: From february 1995 to february 1996, 11 dogs with ultrasonographic signs of prostatic parenchymal cysts had fine needle aspiration of prostatic hypoechoic lesions. The fluid collected was submitted for cytological examination and each dog had a follow-up examination one month later. Results: Of 11 dogs, 7 had unilateral cysts and 4 bilateral for a total of 15 intraparenchymal cysts. Cysts’ diameter was less than 15 mm (small) in 4 dogs, between 15 and 30 mm (medium) in 6 and over 30 mm (large) in 5 dogs, Citology confirmed cysts associated with benign hyperplasia in 10 dogs and was suggestive of prostatic carcinoma in 1 dog which was euthanasized by owner request. All the other dogs improved their condition immediately after the procedure. Recurrence, recorded in 4 dogs after 1 month, were retreated and the final outcome after 6 months follow up is: one dog with bilateral medium cysts underwent surgical drainage; two with large cysts had periodi recurrences; two with medium and large cysts recovered after the second drainage; five with small cysts had a good final outcome. Conclusions: The ultrasound guided fine needle aspiration of prostatic cysts is likely to be curative only in dogs with small parenchymal cysts with urethral communication, but in most instances provides immediate relief of the clinical signs.