Seminal vesicle epithelium as a potential pitfall in the cytodiagnosis of presacral masses - A report of two cases

BACKGROUND: Whenever abdominoperineal resection is performed because of a r ectal adenocarcinoma, the prostate and seminal vesicles may be displaced ba ckward to the presacral space, giving rise to a false radiologic image of a presacral tumor. Due to cytologic atypia associated with the epithelium of seminal vesicles, there is a real possibility, in fine needle aspiration b iopsy (FNAB), of erroneously giving a malignant diagnosis. CASES: Two men, aged 53 and 57 years, presented with presacral masses three months and six years, respectively, after abdominoyerineal resection for r ectal adenocarcinoma. In both cases, FNAB smears showed some groups and sin gle cells with large and irregular nuclei. These cells suggested a recurren ce of carcinoma. The presence of cytoplasmic coarse pigment and a backgroun d with spermatozoa and blobs of inspissated secretory product were sufficie nt to determine that these presacral masses represented the seminal vesicle s. CONCLUSION: Awareness that seminal vesicles may give vise to a radiologic i mpression of presacral tumor after abdominoperineal resection of the rectum will avoid unnecessary FNAB and a cytologic false positive diagnosis of co lorectal adenocarcinoma.