Nuclear staining for pan-Trk by immunohistochemistry is highly specific for secretory carcinoma of breast: pan-Trk in various subtypes of breast carcinoma.

Aims: Secretory carcinoma of breast (SCB) typically harbours gene fusion. Pan-Trk immunohistochemistry analysis (IHC) has been shown to be sensitive for SCB diagnosis. However, weak focal pan-Trk nuclear staining was previously found in 10% of non-secretory breast carcinomas.