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