Usefulness of epithelial membrane antigen (EMA) to discriminate between perineural invasion and perineural indentation in prostatic carcinoma.
OBJECTIVE
Perineural invasion (PNI) is one of the few unequivocal criteria to diagnose adenocarcinoma of the prostate. Distinguishing PNI from perineural indentation (PNIn), however, is sometimes difficult. The aim of this study was to discriminate between PNI and PNIn using EMA immunohistochemistry.


RESULTS
We selected representative sections from 87 prostatectomies with prostatic adenocarcinoma. Normal peripheral nerves were continuously encircled with perineurium, which was immunoreactive for EMA. We identified 1319 PNI by carcinomas, 368 PNIn by carcinomas, and 303 PNIn by benign glands. We categorized the EMA immunoreactivity patterns into three classes: samples that displayed discontinuity or complete loss of the perineurium (Type A), samples where there were carcinomas or benign glands in the perineural space or peripheral nerves (Type B) and samples that showed no changes in the perineurium (Type C). For PNI we observed Type A, Type B, and Type C patterns in 55.3%, 24.8% and 19.9% of carcinomas, respectively. The incidence of each of those patterns in PNIn by carcinomas was 32.1%, 14.9% and 53.0%, respectively. Cases of PNIn by benign glands showed Type A or Type C patterns. They did not, however, exhibit Type B patterns.


CONCLUSIONS
EMA immunostaining will aid the diagnosis of prostatic adenocarcinoma.
Tsuzuki
T
T
Department of Pathology and Laboratory Medicine, Nagoya Daini Red Cross Hospital, 2-9 Myouken-cho, Showa-ku, Nagoya, Japan. tsuzuki@nagoya2.jrc.or.jp
Ujihira
N
N
Ando
T
T
D000230:Adenocarcinoma / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D018396:Mucin-1 / Q000032:analysis*; D009361:Neoplasm Invasiveness; D010525:Peripheral Nerves / Q000737:chemistry / Q000473:pathology*; D010524:Peripheral Nervous System Neoplasms / Q000175:diagnosis / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000473:pathology*; D012680:Sensitivity and Specificity
D018396:Mucin-1