The utility of immunostaining for NUT, GAGE7 and NY-ESO-1 in the diagnosis of spermatocytic seminoma.

AIMS: To identify specific positive immunohistochemical markers for spermatocytic seminoma (SS).

METHODS AND RESULTS: We studied the reactivity of 94 (total) cases of SS, seminoma, embryonal carcinoma and solid yolk sac tumour with antibodies against nuclear protein in testis (NUT) and two cancer/testis antigens, GAGE7 and NY-ESO-1. When tumour positivity was defined as an extent plus intensity score of ≥ 4, NUT was positive in 71% of SSs, 19% of seminomas, and 5% of solid yolk sac tumours. GAGE7 was positive in 67% of SSs and 4% of seminomas. NY-ESO-1 was positive in 82% of SSs, 13% of seminomas, and 5% of solid yolk sac tumours. The sensitivity and specificity, respectively, of these antibodies for SSs were as follows: NUT, 71% and 92%; GAGE7, 67% and 99%; and NY-ESO-1, 82% and 94%. When positivity criteria were stricter, NUT and GAGE7 positivity occurred exclusively in SS, but the sensitivity decreased to 41% and 60%, respectively, and NY-ESO-1 was 59% sensitive and 97% specific. Neither the sarcomatous component of three SSs nor any embryonal carcinoma showed reactivity with any antibody.

CONCLUSIONS: All three antibodies are variably sensitive for SS, and high specificity is attained when there is multifocal and strong nuclear labelling.