2. Causes of common acquired melanosis (melanodermia):

• Addison's disease (tumor or tuberculous damage to the adrenal glands)

• vitamin deficiency (pellagra, scurvy)

• endocrine disorders (hypogonadism, hypopituitarism)

• cachexia

• intoxication with hydrocarbons

Mechanism: decrease in adrenaline formation  increase in ACTH production  increase in the number of melanosomes, stimulation of synthesis of melanin from tyrosine instead of adrenaline  hyperpigmentation of the skin

26. General and local hypermelanosis: causes, mechanisms of development, macro- and microscopic signs, clinical significance.

The cause of common congenital hypermelanosis (xeroderma pigmentosa): an autosomal recessive hereditary defect in the DNA repair system. It is characterized by an increase in skin sensitivity to UV :

• mottled skin pigmentation with hyperkeratosis and edema (in the early stages)

• foci of atrophy, cracks, ulcers, warty growths, severe hyperkeratosis, acanthosis (in later stages)

Local hypermelanosis can be:

1. congenital

2. acquired.

The cause and morphology of local congenital hypermelanosis: a violation in the embryogenesis of the migration of melanoblasts from the neuroectodermal tube into the skin.

Causes and morphology of locally acquired hypermelanosis:

• chronic constipation  hypermelanosis of the colon

• pituitary adenoma, hyperthyroidism, DM  black acanthosis (hyperpigmented skin areas)

• pigmented skin spots: freckles and lentigo (ellipsoid-shaped spot of coal-black color)

• Dubrey's melanosis is smooth dark formations with indistinct contours on the skin and mucous membranes, most often in the elderly, often with a tendency to malignancy

27. General and local hypomelanosis: causes, mechanisms of development, macro- and microscopic signs, clinical significance.

Types of hypomelanosis:

1. Focal(local)

2. Common(common)

Focal hypomelanosis manifests itself in the form of leukoderma (white spot) or vitiligo (multiple white spots) of the skin due to:

• disorders of neuroendocrine regulation of melanogenesis (in hypoparathyroidism, DM)

• formation of AT to melanin (with Hashimoto's goiter)

• neurotrophic disorders (with syphilis, depigmentation foci on the neck - "Venus necklace")

Common hypomelanosis - albinism - manifests itself in the form of:

• absence of melanin in hair follicles, epidermis and dermis, retina and iris (colorless hair, white skin, red iris of the eyes)

• severe photophobia, blepharospasm, skin burns during insolation

The cause of albinism: hereditary tyrosinase deficiency.

28. Calcifications: definition of the concept, types. Metabolism and regulation of calcium is normal.

Disorders of calcium metabolism are called calcification, calcareous dystrophy, or calcification. It is based on the precipitation of calcium salts from the dissolved state and their deposition in cells or intercellular matter. The calcification matrix can be mitochondria and lysosomes of cells, glycosaminoglycans of the main substance, collagen or elastic fibers. In this regard, intracellular and extracellular calcification are distinguished. Types of calcification: it can be systemic (widespread) or local.