Questions to control the knowledge

1. Definition and types of the regeneration.

2. Regeneration of the connective tissue, bones, vessels.

3. Definition of hypertrophy and its types according to the mechanisms of development.

4. Definition of hyperplasia.

5. Definition and types of atrophy.

6. Definition and types of organization.

7. Types of wound healing.

8. The importance of processes of compensatory adaptation for vital functions of the organism.

9. Basic mechanisms of regulation processes of compensatory adaptation.

Terminology

Regeneration, hypertrophy, hyperplasia, restitution, substitution, concentric hypertrophy, regenerative hypertrophy, excentric hypertrophy, false hypertrophy (pseudohypertrophy), vicarious hypertrophy, vacant hypertrophy, atrophy, myogenic dilatation, tonogenic expansion, agenesia, aplasia, hypoplasia, dwarfism, cachexia, brown artophy, hydronephrosis, hydro-cephalia, metaplasia, heterotopia, organization, first intention, secondary intention, encapsulation.

NEOPLASIA

Tumor (neoplasm, blastoma) is a pathological process characterized by unrestrained cell multiplying. Annually, malignant tumors cause 575 000 deaths from gastric cancer, 600 000 from lung cancer, 250 000 from breast cancer. The highest frequency of malignant tumors (242.3-361.1 per 100 000 persons) was registered in Italy, France, Denmark, the USA, Brazil.

The tumors are classified according to histoge-netic principles with the account of their morphological structure, localization, peculiarity of their structure in a definite organ, benign or malignant character.

The classification was suggested as an international one by the Committee on Tumor Nomenclature of the International Anticancer Union. According to this classification, there are 7 groups of tumors, their total number exceeds 200.

1. Epithelial tumors without specific localization (nonorganspecific).

2. Tumors of endocrine and exocrine glands as well as epithelial integument (organspecific).

3. Mesenchymal tumors.

4. Tumors of melanin-forming tissue.

5. Tumors of nervous system and brain membranes.

6. Tumors of blood system.

7. Teratomas.

According to their clinico-morphological characteristics the tumors are divided into 3 groups: 1) benign, 2) malignant, 3) tumors with local destructive growth.

Benign tumors(mature) consist of differentiated mature cells. They are characterized by 1) tissue atypism, that is a property which distinguishes cells and tissues from their normal condition; 2) slow expansive growth; 3) the tumor does not usually influence the organism in general; 4) the tumor does not produce metastases; 5) the relapses are rare. Benign tumors may become malignant.

Malignant(immature) tumors consist of undifferentiated cells. These tumors produce metastases. Metastasis is separation of the tumor cells from the bulk and their transportation to the other organs.

Metastases can be:

1) lymphogenic (they are carried through the lymphatic vessels to regional lymphatic nodes);

2) hematogenic (they are carried with the blood flow to distant organs);

3) implantation (contact), when the tumor disseminates through the serous layers (peritoneum, pleura) and grow to the adjacent organs).

Malignant tumors often relapse. Relapse is appearance of the tumor on the place from which it was removed.

Malignant tumors produce both local and general effect on the organism. A local effect manifests with squeezing and destruction of the surrounding tissues. General effect on the organism is characteristic for all malignant tumors, it manifests with metabolic disturbances and cachexia development.

The tumors with local destructive growth occupy the intermediate place between benign and malignant. They have the features of infiltrating growth but do not give metastases. Malignant tumors are characterized by tissue, cellular, biochemical, histochemical and antigenic atypism as well as that of the ultra-structure.

Depending on the degree of the tumor differentiation, there are different types of its growth: expansive, apposition, infiltrating (invasive).

At expansive growth the tumor grows from itself moving away the surrounding tissues. This type of growth is slow, and is characteristic benign tumors.

Apposition growth is due to transformation of normal cells to tumor ones.

In infiltrating growth the cells of the tumor invade normal tissues and destroy them (so called destructive growth).

In relation to the lumen of the hollow organ, the growth of the tumor may be endophytic or exophytic. Endophytic growth is infiltrating growth of the tumor deep into the wall of the organ. Exophytic growth is expansive growth of the tumor to the cavity of the organ.

According to the number of foci of tumor development, they can be unicenter (one focus) and multicenter (several foci).

Structure of tumor

The appearance of the tumor is various. Its shape may resemble a node, a mushroom cap or cauliflower, a saucer. Its surface may be smooth, bumpy, papillary. The tumor may grow as a node with distinct borders, it may have a limb or a capsule. The size of the tumor can be different. Its consistency depends on prevalence of parenchyma or stroma in it. It may be either soft or solid (dense).

Secondary changes in the tumor result from disturbances of blood circulation in it as well as from chemo- or radiotherapy. They manifest by foci of necrosis, hemorrhages, inflammation, formation of mucus, calcification.

The etiology of tumors is various, 4 theories are recognized.

1. Virogenetic theory. It states integration of the genomes of the virus and the normal cell, that is combination of nucleic acid of the virus with genetic apparatus of the cell which turns into tumor cell. Oncogenic viruses are those containing DNA and RNA (Epstein-Barr virus, herpes virus, hepatitis B virus, etc.).

2. Physicochemical theory suggests that tumor appears under the influence of different physical and chemical substances, so called carcinogens.

3. Dysontogenetic theory was created by J. Cohnheim. According to his theory, tumors appear from embryonic tissue and abnormally developed tissues under the influence of different causative agents.

4. Polyetiological theory emphasizes the importance of different factors, i.e. chemical, physical, viral, parasite, dyshormonal.

MESENCHYMAL TUMORS

In ontogenesis, mesenchyma gives the beginning to: 1) connective tissue, 2) vessels, 3) muscles, 4) tissues of musculoskeletal system, 5) serous membranes, 6) hemopoietic system.

Mesenchymal tumors develop from: 1) connective (fibrous) tissue, 2) fat tissue, 3) muscular tissue, 4) blood and lymphatic vessels, 5) synovial tissue, 6) mesothelial tissue, 7) bone tissue.

They may be benign (name of the tissue + oma) and malignant (name of the tissue + sarcoma). There are also special terms (e.g. desmoid, granular-cell tumor).