Immunohistochemistry:
Both benign and malignant GCTs typically stain positively for S-100, a
neuromelanocytic marker and for CD68 a marker of lysosomal activity.
GCTs also stain positive for neuron-specific enolase, CD57, inhibin,
calretinin, TFE3, SOX10, CD56, PGP9.5, and vimentin [11,14,33-36].
S-100 is strongly positive for GCT but is not specific since it can be
seen in melanoma, micro glandular adenosis, and typically negative in
breast carcinomas [11]. Some GCT have been described in pregnancy
[37] and the immunohistochemical profile shows no hormonal
dependence. GCTs lack estrogen or progesterone receptor and cytokeratin
expression [14]. Microscopically, GCTB can resemble apocrine
carcinoma, but GCTB lacks androgen receptors and apocrine carcinoma
lacks S100 expression. AE1/3 epithelial markers can also help
distinguish GCTB from invasive carcinoma because they stain negative in
GCTB [14].