Download MBBS Dermatology PPT 21 Pigmentary Disorders Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Dermatology PPT 21 Pigmentary Disorders Lecture Notes


PIGMENTARY

DISORDERS

Neirita Hazarika

INTRODUCTION

? Human skin colour ? unique

? Varies with race, climate, light exposure,

ethnic and individual skin constitution,

lifestyle and anatomical regional variations

? Basic pigments ? MELANIN, Hb, caretenoids


MELANOCYTE

? Dendritic cells
? Develop from melanoblasts
? Light microscopy: clear cells in and immediately

beneath the basal layer of epidermis.

? On H&E stain: an avg 1 melanocyte / 10

keratinocytes.


EPIDERMAL MELANIN UNIT

1 melanocyte 36 keratinocytes
FUNCTION OF MELANIN

Protection - scattering and absorbing UV

light

Neutraliser of toxic, free radical oxygen

derivatives, by products of various

inflammatory processes.

Impart different colour to hair - black,

blond,brunette,red

CLASSIFICATION OF

PIGMENTARY DISORDERS

Hyperpigmentary

Hypopigmentary

Depigmentary
HYPOPIGMENTARY AND

DEPIGMENTARY DISORDERS

Developmental anomaly ? nevus

depigmentosus

Genetic ? albinism, piebaldism,tuberous

sclerosis, phenylketonuria

Endocrine ? Addison's disease,

hyperthyroidism

Nutritional ? kwashiorkar, ulcerative

colitis

Chemicals & Drugs ? phenol,

corticosteroids, retinoic acid

Post inflammatory
Mechanical - burns, radiation
Infective ? p.versicolor, leprosy, syphilis,

herpes
Non infective - P.alba, morphea,

psoriasis, DLE

Miscellaneous ? vitiligo, halo nevus
Affecting hair alone - alopecia areata
VITILIGO

Common disorder characterised by well circumscribed milky

white macules (due to loss of melanocytes) with scalloped

margin

Pathogenic mechanisms:

Autoimmune destruction of melanocytes
An intrinsic defect in melanocytes, their adhesive

properties and/or factors critical to their survival

Defective defense against oxidative stress leading to

destruction of melanocytes


HPE

absence of

melanin granules

and gross lack of

dopa positive

melanocytes in

the basal layer.

Can affect the

melanocytes of

the hair.
















Leukotrichia


WOOD'S Lamp Examination

Koebner's phenomenon


Childhood vitiligo

positive family history,
few lesions,
segmental,
difficult to Rx,
better prognosis

Associations

Dm,
Thyroid Disorders,
Pernicious Anemia,
Addison's Disease







Pityriasis versicolor

Pityriasis Alba




TREATMENT : MEDICAL


TREATMENT : SURGICAL

done only in stable vitiligo + refractory to

medical treatment

1.Grafting ? punch,split skin thickness,blister
2.Tattooing
3.Dermabrasion
4.Melanocyte culture and transplantation




HYPERPIGMENTARY

DISORDERS

Classification is based on level of

hyperpigmentation and extent of

involvement.

MACULAR PIGMENTATION ?
Small macule ? freckles,lentigenes
Large macule ? caf?-au-lait spots,mongolian

spot,Becker's nevus
Irregular pigmentation ? PIH
Generalised diffuse ? tanning


DIFFUSE PIGMENTATION

Addison's disease
Nutritional disorders ? Vit B12 defiency,

Pellagra

Connective tissue diseases ? systemic

sclerosis

Metabolic ? cirrhosis,Wilson's disease
Malignancy






DRUGS ?
Focal ? FDE (barbiturates , phenolphthalein)
Diffuse ? clofazamine, antimalarials, busulfan

FACIAL MELANOSIS ?
heterogenous ,multifactorial ,can be patchy and

diffuse,most common over the face and neck
Eg: melasma, lichen planus pigmentosus


MELASMA
Acquired ,circumscirbed, pigmentary

disorder

characterized by symmetrically

distributed brown macules with defined
borders involving the face

CAUSES

sunlight ,
hormonal (pregnancy),
genetic,
toxic (cosmetics),
drugs(OCP).

Pathogenesis
Increase in melanocyte number and

activity

increase in formation,size and

melanization of melanosomes
CLASSIFICATION

1.Clinical :
Acc to distribution ?

central facial,
malar,
mandibular

Acc. to wood `s lamp ?

epidermal,
dermal,
mixed

2.Histopathological :

epidermal,
dermal

TREATMENT

1. Sun protection
2. Topical depigmenting agents

Steroids + hydroquinone + retinoids ?in

combination(Kligman's)

Azelaic acid
Kojic acid
Glycolic acid

3. Chemical peels
4. Lasers




WOOD'S LAMP

high pressure mercury

arc

fitted with a compound

filter made of barium

silicate with 9% nickel

oxide "Wood's filter".

opaque to al light rays

except a band between

320 and 400 nm with a

peak at 365 nm.

Technique of Wood's lamp

examination

The lamp allowed to warm up for about 1 minute.
Examination room perfectly dark & windowless.
The light source4 to 5 inches from the lesion.
Washing the area
Examine


Applications of Wood's lamp

Tinea capitis

Pityriasis Versicolor
Malassezia furfur emits a yellowish-white or copper-orange

fluorescence

Applications of Wood's lamp

Pseudomonas species produce a pigment 'pyoverdin' or

'fluorescein' which shows green fluorescence

Erythrasma - Corynebacterium minutissimum shows coral red

fluorescence

P. acnes - imparts orange-red fluorescence to the comedones
Melasma - Wood's lamp can be used to determine the depth of

melanin in the skin.

Wood's lamp is therefore helpful in making a diagnosis of

vitiligo

Detection of excess porphyrins in the teeth, urine, stool

samples, red blood cel s and blister fluid in different forms of

porphyrias


THANK YOU

This post was last modified on 07 April 2022