A = section of mucosa shows tumour infiltration of the underlying stroma. Surface is ulcerated (hematoxylin and eosin stain, original magnification x40).
B = small cell carcinoma. Tumour cells are densely packed, with scant cytoplasm, finely granular nuclear and absence of nucleoli (hematoxylin and eosin stain, original magnification x400).
C = large cell component of the neoplasm has more cytoplasm and prominent nucleoli (hematoxylin and eosin stain, original magnification x400).
D = TTF1 immunoreactivity with a typical nuclear pattern (original magnification x100).
E = chromogranin immunostaining shows a granular cytoplasmic pattern (original magnification x100).
F = synaptophysin immunoreactivity with membranous staining pattern (original magnification x100).