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Download MBBS Dermatology PPT 21 Pigmentary Disorders Lecture Notes

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

This post was last modified on 07 April 2022

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Neirita Hazarika

INTRODUCTION

? Human skin colour ? unique

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? Varies with race, climate, light exposure,

ethnic and individual skin constitution,

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lifestyle and anatomical regional variations

? Basic pigments ? MELANIN, Hb, caretenoids


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MELANOCYTE

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

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beneath the basal layer of epidermis.

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

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keratinocytes.


EPIDERMAL MELANIN UNIT

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1 melanocyte 36 keratinocytes
FUNCTION OF MELANIN

Protection - scattering and absorbing UV

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light

Neutraliser of toxic, free radical oxygen

derivatives, by products of various

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inflammatory processes.

Impart different colour to hair - black,

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blond,brunette,red

CLASSIFICATION OF

PIGMENTARY DISORDERS

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Hyperpigmentary

Hypopigmentary

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Depigmentary
HYPOPIGMENTARY AND

DEPIGMENTARY DISORDERS

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Developmental anomaly ? nevus

depigmentosus

Genetic ? albinism, piebaldism,tuberous

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sclerosis, phenylketonuria

Endocrine ? Addison's disease,

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hyperthyroidism

Nutritional ? kwashiorkar, ulcerative

colitis

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Chemicals & Drugs ? phenol,

corticosteroids, retinoic acid

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

herpes

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Non infective - P.alba, morphea,

psoriasis, DLE

Miscellaneous ? vitiligo, halo nevus

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Affecting hair alone - alopecia areata
VITILIGO

Common disorder characterised by well circumscribed milky

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white macules (due to loss of melanocytes) with scalloped

margin

Pathogenic mechanisms:

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

properties and/or factors critical to their survival

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Defective defense against oxidative stress leading to

destruction of melanocytes

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HPE

absence of

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melanin granules

and gross lack of

dopa positive

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melanocytes in

the basal layer.

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Can affect the

melanocytes of

the hair.

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Leukotrichia


WOOD'S Lamp Examination

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Koebner's phenomenon


Childhood vitiligo

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

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better prognosis

Associations

Dm,

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Thyroid Disorders,
Pernicious Anemia,
Addison's Disease


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Pityriasis versicolor

Pityriasis Alba


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TREATMENT : MEDICAL


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TREATMENT : SURGICAL

done only in stable vitiligo + refractory to

medical treatment

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

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HYPERPIGMENTARY

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DISORDERS

Classification is based on level of

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hyperpigmentation and extent of

involvement.

MACULAR PIGMENTATION ?

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

spot,Becker's nevus
Irregular pigmentation ? PIH

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Generalised diffuse ? tanning


DIFFUSE PIGMENTATION

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Addison's disease
Nutritional disorders ? Vit B12 defiency,

Pellagra

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Connective tissue diseases ? systemic

sclerosis

Metabolic ? cirrhosis,Wilson's disease

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Malignancy




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

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FACIAL MELANOSIS ?
heterogenous ,multifactorial ,can be patchy and

diffuse,most common over the face and neck

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Eg: melasma, lichen planus pigmentosus


MELASMA
Acquired ,circumscirbed, pigmentary

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disorder

characterized by symmetrically

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distributed brown macules with defined
borders involving the face

CAUSES

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

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Pathogenesis
Increase in melanocyte number and

activity

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increase in formation,size and

melanization of melanosomes
CLASSIFICATION

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1.Clinical :
Acc to distribution ?

central facial,

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malar,
mandibular

Acc. to wood `s lamp ?

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epidermal,
dermal,
mixed

2.Histopathological :

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epidermal,
dermal

TREATMENT

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1. Sun protection
2. Topical depigmenting agents

Steroids + hydroquinone + retinoids ?in

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combination(Kligman's)

Azelaic acid
Kojic acid

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Glycolic acid

3. Chemical peels
4. Lasers

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WOOD'S LAMP

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high pressure mercury

arc

fitted with a compound

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filter made of barium

silicate with 9% nickel

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oxide "Wood's filter".

opaque to al light rays

except a band between

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320 and 400 nm with a

peak at 365 nm.

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Technique of Wood's lamp

examination

The lamp allowed to warm up for about 1 minute.

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Examination room perfectly dark & windowless.
The light source4 to 5 inches from the lesion.
Washing the area
Examine

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Applications of Wood's lamp

Tinea capitis

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

fluorescence

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Applications of Wood's lamp

Pseudomonas species produce a pigment 'pyoverdin' or

'fluorescein' which shows green fluorescence

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Erythrasma - Corynebacterium minutissimum shows coral red

fluorescence

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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.

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

vitiligo

Detection of excess porphyrins in the teeth, urine, stool

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

porphyrias

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THANK YOU