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 PigmentationLack 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 PigmentationLack 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 PigmentationLack generalized

– total albinism

– parcial albinism

local– vitiligo

– leucoderma

Leucoderma

postinflammatory

circumscribed depigmentation

e.g.

– leucoderma syphyliticum

– leucoderma psoriaticum

Disorders of Melanin PigmentationIncrease generalized

– Adison disease

local– freckles, nevi– chloasma /melasma– melanodermia– melanoma

Disorders of Melanin PigmentationIncrease 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

MELANINNorepinephrineEpinephrine

3

1

2

Homogentisicacid

cc

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