General Pathology

Basic Principles of Cellular and Organ

Pathology

Autogenous

Pigments

Jaroslava Dušková

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

PigmentsDefinition:

colored substances

in the organism

or environment

PigmentsClassification:

� 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 H2O2

� reducing AgNO3

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 Tyrosine

methyl–

acetoacetic

acid

DOPA

MELANINNorepinephrine

Epinephrine

3

1

Homogentisic

acid

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