General Pathology Basic Principles of Cellular and Organ Pathology

Autogenous Pigments

Jaroslava Dušková

Inst. Pathol. ,1st Med. Faculty, Charles Univ. Prague

Pigments

Definition:

colored substances in the organism or environment

Pigments

Classification:

 endogenous   autogenous hemoproteins derived  exogenous

Autogenous Pigments

-

color substances formed in the organism as metabolism products

 

melanin ceroid



lipofuscin

Melanin

 oculocutaneous

(origin from tyrosine in melanocytes)

 neuromelanin - subst. nigra

(origin from dopamin)

Melanin

- types

 eumelanin – insoluble , brown-black  phaeomelanin – soluble, yellow-red (

high sulphur content)

Melanin

- production

Melanocytes – derived from the neural crest – present in the basal layer of epidermis, dermis, hair folicles, mucose membranes, uveal tract of the eye, meninges, inner ear – secretory in the contact with the epithelial cells - cytocrinia

Melanin Functions – 1.

 cytoprotective – light absorption & conversion of the photon energy into heat – uvea – absorption of the light retina protection of light overexposure – retina - visual acuity preventing light reflexion from the fundus

Melanin Functions -2.

 Ion exchanging capacity Melanosomes can also act as detoxyfiing and excretory components accumulating great number of drugs and toxic component e.g. heavy metals. Scavengers of the free radicals.

Rarely cytotoxic – photosensibilisation

Melanin - Features

   brown destained with H 2 O 2 reducing AgNO 3

Disorders of Melanin Pigmentation

Lack 

generalized

–

total albinism

–

parcial albinism



local

–

vitiligo

–

leucoderma

Albinism  autosomal recessive heredity – tyrosinase deficiency – tyrosinase positive – melanosomes defect  oculo-cutaneous albinoidism –

dominant inheritance

Disorders of Melanin Pigmentation

Lack 

generalized

–

total albinism

–

parcial albinism



local

–

vitiligo

–

leucoderma

Vitiligo  familial aggregation  polygenic nature  association with other autoimmune diseases

(DM, thyroiditis, gastritis)

 ab against tyrosinase in the serum  autoreact . T- cellular cytotoxicity

Disorders of Melanin Pigmentation

Lack 

generalized

–

total albinism

–

parcial albinism



local

–

vitiligo

–

leucoderma

Leucoderma

 postinflammatory circumscribed depigmentation e.g.

– leucoderma syphyliticum – leucoderma psoriaticum

Disorders of Melanin Pigmentation

Increase 

generalized

–

Adison disease



local

–

freckles, nevi

–

chloasma /melasma

– –

melanodermia melanoma

Disorders of Melanin Pigmentation

Increase 

generalized

–

Adison disease



local

–

freckles, nevi

–

chloasma

– –

melanodermia melanoma

Disorders of Phenylalanine and Tyrosine Metabolism 1. Phenylalanine hydroxylase PHENYLKETONURIA 2. Homogentisic acid oxydase ALKAPTONURIA 3. Tyrosinase ALBINISM

Disorders of Phenylalanine and Tyrosine Metabolism Phenylalanine

1

Tyrosine

3 Homogentisic acid

DOPA

methyl – acetoacetic acid Norepinephrine Epinephrine MELANIN

Ceroid



features

– light brown – PAS + – acidoresistent – Sudan + 

origin

– – fagocytosis od lipid substances by macrophages oxidation of non –saturated lipid acids

Ceroid



localisation

– – – – – places of erythrocytes destruction necroses of adipous tissue avitamonosis E melanosis coli Dubin - Johnson syndrome

Lipochrom

   

ubiquitous pigment exogenous origin lipid solvent histologically unprovable

Lipofuscin



features

– dark brown – Sudan + – autofluorescence

Lipofuscin

 origin – autophagocytosis "wear and tear" pigment from the accumulation of autophagolysosomes over time.

Lipofuscin

 localisation – CNS, epithels, muscles, liver

ATROPHIA FUSCA