Pleomorphic adenoma –the tumour at the left side is white gray firm lobulated mass without hemorrhage or necrosis. note the normal lobulated gland at the right

Pleomorphic adenoma –note the myxoid stroma with proliferated ducts & glands & scattered myoepithelial cells

Benign papillary cystadenoma lymphomatosum, or Warthin's tumor, cystic spaces filled with serous fluid with papillary projections which are covered by double layers of oncocytic epithelium overlying lymphoid stroma some with germinal center

Adenoid cystic carcinoma of salivary gland, solid growth of small hyperchromatic neoplastic cells surrounding small (microcystic) spaces filled with mucinous secretions giving rise to cribriform appearance

"Barrett's esophagus" in which there is mucus secreting epithelium with goblet cells (intestinal metaplasia) in the lower segment of esophagus.

This irregular reddish, ulcerated exophytic mid-esophageal mass as seen on the mucosal surface is a squamous cell carcinoma. Risk factors for esophageal squamous carcinoma include mainly smoking and alcoholism. Diagnosis: Carcinoma of esophagus, mostly squamous cell carcinoma

Acute gastritis: hyperemic erythmatous edematous gastric mucosa with foci of superficial erosions. There are many causes for acute gastritis: alcoholism, drugs, infections, etc

H-pylori This small curved to spiral rod-shaped bacterium is found in the surface epithelium of most patients with active gastritis. The rods are seen here with a methylene blue stain.

Chronic gastric ulcer: the ulcer is rounded covered by necrotic surface , note the radiating thickened mucosal folds due to underlying fibrosis.

Chronic peptic ulcer the ulcer here is sharply demarcated with base contains necrotic debris with underlying fibrosis, surrounded by hyperplastic gastric mucosa

Gastric carcinoma: the mass is large fungating irregular whitish-gray mass within the body portion of the stomach.

This is an example of linitis plastica, a diffuse infiltrative gastric adenocarcinoma which turns the stomach into a shrunken "leather bottle" appearance. Diagnosis: gastric carcinoma, diffuse infiltrative type

Signet ring carcinoma of stomach, This is a signet ring cell pattern of gastric carcinoma in which the cells are filled with mucin vacuoles that push the nucleus to one side

Pseudomembranous colitis of the colon Pseudomembranous colitis of the colon. The mucosal surface of the colon seen here is hyperemic edematous and is partially covered by a yellow-green exudates.

Normal villi on the left side & total villus atrophy with crypts hyperplasia & increase inflammatory cells on the right side, in Celiac disease

Ulcerative colitis: pseudopolyps, The mucosa becomes eroded, the surrouinde mucosa inflammed & edematous which bulging above the eroded areas giving rise to polypoidal appearance.

Adenomatous polyp (tubular adenoma) have more crowded, disorganized glands with some dilated ducts, goblet cells are less numerous ,the polyp is connected to the underlying mucosa by a stalk.

Multiple nodules of different sizes attached to colonic mucosa by a stalk Diagnosis: adenomatous polyp

Familial Polyposis coli, with numerous small polyps variable covering the colonic mucosa. there is a 100% risk over time for development of adenocarcinoma

Villus adenoma , composed of large number frond-like projections & connected to the mucosa without stalk (sessile) such adenoma has an increased risk of development of carcinoma overtime.

Carcinoma ofcolon, an ulcerative lesion with a heaped up margin of tumor at each side Diagnosis colonic carcinoma- ulcerative type.