Evaluation of the cytologic diagnosis of canine prostatic disorders.

Background: Canine prostatic disease is commonly investigated using cytologic techniques, especially now that ultrasound-guided fine needle cell aspiration (US-FNA) is widely available. Few studies, however, have evaluated the diagnostic accuracy of prostatic cytology.

Objective: The purpose of this study was to evaluate the usefulness of cytologic investigation of prostatic disease using US-FNA and other methods in comparison with histopathologic diagnosis.

Methods: Cytologic and histopathologic specimens of prostate or paraprostatic tissue from 25 adult dogs were retrospectively evaluated. Cytologic samples were obtained by US-FNA, prostatic massage, or direct impression smears or aspirates of tissue at surgery. Histopathologic sections were obtained from tissue collected by biopsy or at necropsy.

Results: Cytologic diagnoses were categorized as nondiagnostic (n = 2); cyst (n = 1); squamous metaplasia (n = 2); inflammation (n = 4); benign prostatic hyperplasia (BPH; n = 5); inflammation and BPH (n = 3); inflammation, BPH, and neoplasia (n = 1); inflammation and neoplasia (n = 3); and neoplasia (n = 4). Cytologic diagnoses agreed with final histologic diagnoses in 20 of the 25 cases (80%). Of those samples collected by US-FNA, 75% were concordant. Four samples obtained by US-FNA and 1 sample obtained by prostatic massage and wash had discordant results.

Conclusions: The results of this study suggest strong agreement between cytologic and histopathologic diagnoses for prostatic conditions. Discordance in results obtained by US-FNA usually was the result of the pathologic process rather than a failure to obtain an appropriate sample.