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

Whenever abdominoperineal resection is performed because of a rectal adenocarcinoma, the prostate and seminal vesicles may be displaced backward 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 biopsy (FNAB), of erroneously giving a malignant diagnosis. Two men, aged 53 and 57 years, presented with presacral masses three months and six years, respectively, after abdominoperineal resection for rectal adenocarcinoma. In both cases, FNAB smears showed some groups and single cells with large and irregular nuclei. These cells suggested a recurrence of carcinoma. The presence of cytoplasmic coarse pigment and a background with spermatozoa and blobs of inspissated secretory product were sufficient to determine that these presacral masses represented the seminal vesicles. Awareness that seminal vesicles may give rise to a radiologic impression of presacral tumor after abdominoperineal resection of the rectum will avoid unnecessary FNAB and a cytologic false positive diagnosis of colorectal adenocarcinoma.