The significance of atypia in fine needle aspiration cytology of the prostate.

Of 411 fine needle aspirates of the prostate 208 could be matched with conventional pathological material. Cytological diagnosis had a complete sensitivity of 94 per cent, specificity 99 per cent and efficiency 74 per cent. Corresponding figures for 36 patients who underwent total prostatectomy were complete sensitivity 100 per cent, specificity 100 per cent and efficiency 78 per cent. Atypical cytology results not amounting to frank malignancy were the main reasons for reduced efficiency and, therefore, analysis of the significance of atypia was performed. In 50 aspirates from 43 patients atypia of varying degree was noted but the degree of atypia did not allow for a diagnosis of malignancy. Subsequent diagnosis of carcinoma was made by cutting needle biopsy or transurethral resection in 7 of 14 specimens (50 per cent) of severe, 3 of 9 (33 per cent) moderate, 3 of 7 (43 per cent) mild and 3 of 16 (19 per cent) reactive atypia. Thus, specific cytological diagnoses have a high degree of accuracy but atypia and attempts to categorize it did not predict accurately the final diagnosis. Pathological conditions that may account for atypia in fine needle aspiration cytology are reviewed.