1.* Papilloma (papilloma) Benign tumors occurring from complex layers of overlying epithelium, such as squamous epithelium or migratory epithelium. The tumor grows exophytically to the surface, forming many finger-like or *-like projections, and may have a cauliflower-like or fluffy appearance. The roots of the tumor often have fine tips attached to normal tissue. Microscopically, each *surface is covered with hyperplastic squamous or migratory epithelium, and the *axis is composed of branching connective tissue mesenchyme with blood vessels. Squamous epithelial *granulomas are clinically common on the vulva, nasal cavity, and larynx. Its occurrence may be related to infection with human *squamous tumor virus. Squamous epithelial *squamous tumors of the external auditory canal and penis are more likely to undergo malignant transformation and form squamous cell carcinoma. Migratory epithelial *like tumors are seen in the bladder, ureter, and renal pelvis. Migratory epithelial *like tumors of the bladder are more likely to become malignant.

2. Adenoma is a benign tumor arising from glands, ducts, or secretory epithelium, and is most common in the thyroid, ovaries, breast, salivary glands, and intestines. Adenomas of the mucosal glands tend to be polypoid. Adenomas in glandular organs are often nodular and often have a peripheral membrane that clearly demarcates them from the surrounding normal tissues. The glands of adenomas are not only morphologically similar to the glands from which they originate, but also often have a certain secretory function, but the arrangement is structurally different.

According to the composition or morphology of adenomas, they can be divided into cystic adenomas, fibrous adenomas, pleomorphic adenomas and polypoid adenomas.

(1) Cystadenoma: Due to the accumulation of glandular secretions in the adenoma, the glandular cavities are gradually enlarged and fused with each other, and cystic cavities of varying sizes can be seen on the naked eye. Cystadenomas are often found in the ovary and occasionally in the thyroid and pancreas. There are two main types of ovarian cystadenomas: one is the growth of glandular epithelium into the cystic cavity in the form of * and secretion of plasma, so it is called plasma * cystadenoma (serous papillary cystadenoma); the other secretion of mucus, often polyhomogeneous, with smooth cystic walls and few * proliferations, so it is called mucinous cystadenoma (mucinous cystadenoma). Mucinous cystadenoma. Among them, plasma * cystadenoma is more prone to malignant transformation, transformed into serous cystadenocarcinoma (serous cystadenocarcinoma).

(2) Fibroadenoma: often occurring in the female breast, is a common benign tumor of the breast. The tumor has a complete envelope, and the section is lobulated and fissured. Microscopically, there is dilatation of the ducts and epithelial hyperplasia; interstitial fibrous hyperplasia is obvious with mucinous changes, often squeezing the ducts. Previously, it was thought that the glands and mesenchyme of fibroadenoma **** the same as constitute the tumor parenchyma, but recently it has been proved that the hyperplastic mesenchyme is the substance of the tumor.

(3) pleomorphic adenoma (pleomorophic adenoma): by the glandular tissue, mucus-like and cartilaginous tissue and other components of mixed composition. It often occurs in salivary glands, especially parotid glands, and used to be called mixed tumor. Nowadays, it is generally believed that this tumor is a kind of adenoma occurring from parotid intercalary duct epithelial cells and myoepithelial cells. It is characterized by pleomorphism due to the presence of a mucus-like stroma between the proliferating myoepithelial cells, which may metaplasia into cartilage-like tissue. This tumor grows slowly, but can recur after excision, and a few can develop malignant changes.

(4) Polypous adenoma: also known as adenomatous polyps. Occurs in the mucosa, can be polypoid, * or villous, with a tip and mucosa connected. Most common in the rectum and colon. If the surface is * or villous, the rate of malignancy is higher. Multiple adenomatous polyposis coli often has family heredity, not only the cancer rate is high, and prone to early onset of cancer.