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

Abstract

To identify specific positive immunohistochemical markers for spermatocytic seminoma (SS). 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. All three antibodies are variably sensitive for SS, and high specificity is attained when there is multifocal and strong nuclear labelling.