Fig. 4

Microscopic image of lesion (O) at Fig. 3. a Hematoxylin–eosin (HE) staining, b Periodic Acid-Schiff (PAS) and alcian blue staining, and c immunostaining of pan-cytokeratin (clone: AE1/AE3). HE staining shows that atypical cells with hyperchromatic nuclei were proliferating in the lamina propria. The lesion contains PAS staining positive, pan-cytokeratin (clone: AE1/AE3) positive cells. No lymphatic or vascular invasion was observed