Eosinophilic prostatitis and prostatic specific antigen.

Eosinophilic prostatitis is a rare form of abacterial prostatitis with uncertain aetiology. Its clinical presentation, like other types of abacterial prostatitis, commonly mimics carcinoma of the prostate. Transrectal ultrasound may be helpful in the diagnosis of prostatitis but histological confirmation is necessary. Prostatic specific antigen has been widely used in the diagnosis and follow-up of patients with prostatic carcinoma. High levels of this antigen (greater than 30 micrograms/l) have been claimed to be highly specific for prostate cancer, although lesser elevations may also occur in patients with large benign prostate glands and in bacterial prostatitis. We report 3 patients with histologically proven eosinophilic prostatitis and high levels of prostatic specific antigen. This diagnosis may closely mimic carcinoma of the prostate and must be excluded by histological examination of biopsy material before treatment for presumed prostate carcinoma is initiated.