Slide 1
Adenomas are neoplastic polyps. Although by definition benign, carcinoma may arise in adenomas and for this reason they are considered to be premalignant lesions. Adenomas may be sessile or pedunculated, the two in this kodachrome being examples of the latter. Notice that each of these adenomas has a neoplastic, polypoid head (H) attached to a long stalk (S) of normal colonic mucosa. The sections in your class set were taken through the larger polyp at left (Slide 2).

Slide 2
This is a low power view of the glass slide in your class set. You can easily recognize the polypoid head (H) attached to the long stalk (S) of normal colon.

Slide 3
Is a higher magnification of the junction of the stalk and the head of the adenoma. Note the hypercellularity of the adenomatous epithelium. The mucosa of the head of the polyp is considerably thicker than that of the stalk of the adenoma. The mucosa of the head of the adenoma shows elongated tubular structures as well as occasional villus formations, and for this reason this adenoma would be classified as a tubulovillous adenoma. Also notice the complex granular pattern of the adenoma. The adenomatous glands display lateral branching from the middle and upper regions of the crypts unlike normal crypts which increase in number by bifurcation at their bases, and some cystically dilated glands are present as well.