Table 1. Supplementary histopathologic diagnostic investigations in lung cancer.

Histomorphologic classification	Supplementary investigations required
Squamous cell carcinoma with intercellular bridges and/or keratin pearls	None
Non–small-cell carcinoma	PAS–diastase, p40, TTF1, CD56
Neuroendocrine tumor or large-cell neuroendocrine carcinoma	Chromogranin A, synaptophysin, CD56, TTF1, Ki-67
Small-cell neuroendocrine carcinoma	CD56, synaptophysin, TTF1, Ki-67
Sarcomatoid carcinoma	Pan-CK, CD56, p40, TTF1, S100 protein, desmin, CD31
Metastases	Depend on the primary tumor

CK, cytokeratin; CD, cluster of differentiation; Ki67, Kiel antigen no. 67;

TTF1, thyroid transcription factor 1; PAS, periodic acid–Schiff reaction