Squamous Cell Carcinoma of the Esophagus  Slide 5
Shows nests of malignant squamous cells within the submucosa. This is a moderately differentiated squamous cell carcinoma in that there is keratin production. The malignant cells show a common feature of malignancy, namely altered polarity. The differentiating squamous cells within the submucosal nests cannot slough keratin to the luminal surface. Instead the keratin accumulates in the center of the nests as spherical keratin "pearls" (arrow).

Squamous Cell Carcinoma of the Esophagus (62000-80713) Slide 6
Shows the moderately differentiated squamous cell carcinoma with keratin pearls at higher power.

Squamous Cell Carcinoma of the Esophagus (62000-80713) Slide 7
Mitotic figures are usually common in malignant tumors and often they are abnormal. This is a tripolar mitosis and if you look carefully you can see 3 mitotic spindles.