Dermatology 12 - Disorders of Pigmentation PDF

DISORDERS OF PIGMENTATION  DISORDERS OF PIGMENTATION - NORMAL PIGMENTATION OF THE SKIN IS INFLUENCED BY THE AMOUNT & DEPTH OF MELANIN, BY THE DEGREE OF VASCULARITY, PRESENCE OF CAROTENE AND BY THE THICKNESS OF THE HORNY LAYER. - BROWNNESS OF THE SKIN IS DEPENDENT UPON...

DISORDERS OF PIGMENTATION  DISORDERS OF PIGMENTATION - NORMAL PIGMENTATION OF THE SKIN IS INFLUENCED BY THE AMOUNT & DEPTH OF MELANIN, BY THE DEGREE OF VASCULARITY, PRESENCE OF CAROTENE AND BY THE THICKNESS OF THE HORNY LAYER. - BROWNNESS OF THE SKIN IS DEPENDENT UPON THE TRANSFER OF MELANOSOMES FROM MELANOCYTES INTO KERATINOCYTES. - MELANOSOMES ARE CYTOPLASMIC PARTICLES FORMED IN MELANOCYTES & DISTRIBUTED AMONG THE BASAL CELLS OF THE EPIDERMIS. EACH MELANOCYTE IN THE EPIDERMIS SECRETES MELANOSOMES INTO THE SURROUNDING KERATINOCYTES TO FORM THE EPIDERMAL MELANIN UNIT. THE MELANOSOMES ARE THE SITES OF MELANIN SYNTHESIS BY THE ACTION OF TYROSINASE UPON TYROSINE.  THE VARIATIONS IN SKIN COLOR BETWEEN PERSONS & RACES ARE DUE TO THE DEGREE OF MELANIZATION OF MELANOSOMES, THEIR NUMBER, & THEIR DISTRIBUTION IN THE EPIDERMAL MELANIN UNIT. EPHELIDES – FRECKLES - TAN MACULES < 5 MM IN DIAMETER ON SUN-EXPOSED AREAS LIKE THE NOSE, CHEEKS, HANDS AND UPPER TRUNK - ONE OF THE FIRST INDICATORS OF SOLAR DAMAGE - INCREASE IN MELANIN PRODUCTION WITHOUT MELANOCYTE PROLIFERATION - MELANOCYTES ARE ONE-THIRD LESS ABUNDANT THAN IN ADJACENT NORMAL SKIN BUT ARE LARGER AND CONTAIN MORE MATURE MELANOSOMES - INCREASED IN SUMMER BUT DECREASED DURING WINTER - TREATED BEST WITH PEELING AGENTS & DEPIGMENTING CREAMS - SUN EXPOSURE IS LIMITED IF AT BEST AVOIDED / APPLY SUNSCREENS  MELASMA - CHLOASMA FACIEI - BROWN MACULES ON THE MALAR PROMINENCES & FOREHEAD - EXACT CAUSE IS UNKNOWN ALTHOUGH SUN EXPOSURE, CONTRACEPTIVE PILL INTAKE & GENETIC PREDISPOSITION ARE IMPORTANT FACTORS - OCCURS DURING PREGNANCY AND CLEARS WITHIN A FEW MONTHS AFTER DELIVERY - SEEN ALSO IN MENOPAUSE, OVARIAN DISORDERS AND IN PEOPLE TAKING DILANTIN, TETRACYCLINE. - MAY BE TREATED WITH BLEACHING, DEPIGMENTING CREAMS, LASERS, PROCEDURES LIKE CHEMOBRASION , IONTOPHORESIS AND SUNSCREEN USE. MELASMA  OCHRONOSIS - DERIVED FROM THE GREEK WORD “OCHRE” MEANING YELLOW DISCOLORATION - 2 FORMS : A) ENDOGENOUS B) EXOGENOUS EXOGENOUS OCHRONOSIS - MAJORITY OF CASES HAVE BEEN REPORTED IN DARKER RACIAL/ ETHNIC GROUPS IN AFRICA, INDIA, THAILAND, CHINA, & SINGAPORE - EXACT WORLDWIDE INCIDENCE IS UNKNOWN BUT ASSUMED TO BE LOW  CLINICAL FEATURES: - ASYMPTOMATIC BLUE-BLACK & GRAY-BLACK HYPERPIGMENTED MACULES - FOUND ON FACE ( MALAR, TEMPLES, LOWER CHEEKS), POSTEROLATERAL NECK, BACK & EXTENSOR SKIN OF EXTREMITIES - LATER STAGES INCLUDE PROGRESSIVE HYPERPIGMENTED COLLOID MILLIUM ( CAVIAR-LIKE LESIONS), PAPULONODULAR LESIONS, & AREAS OF SCARRING - NO SYSTEMIC INVOLVEMENT IS NOTED  ETIOLOGY & PATHOGENESIS: - RESULTS FROM THE USE OF CERTAIN MEDICATIONS, W/C FORM A HOMOGENISTIC ACID POLYMER-LIKE SUBSTANCE DURING THEIR METABOLISM - MOST FREQUENTLY REPORTED IN ASSOCIATION W/ 4% HYDROQUINONE, & TOPICALS SUCH AS PHENOL OR RESORCINOL, & QUININE, AN ORAL ANTIMALARIAL - EXACERBATING FACTORS INCLUDE UNPROTECTED ULTRAVIOLET LIGHT EXPOSURE, PROLONGED APPLICATION OF THE OFFENDING MEDICATION ON LARGE SURFACE AREAS & USE OF TOPICAL RESORCINOL, PHENOL & MERCURY  DIAGNOSIS: - ALTHOUGH EARLY STAGES MAY APPEAR SIMILAR TO MELASMA, DERMOSCOPY MAY BE HELPFUL IN DIFFERENTIATING THE TWO - DARK-BROWN GLOBULES AND GLOBULAR-LIKE STRUCTURES ARE SEEN ON A DIFFUSE BROWN BACKGROUND - SKIN BIOPSY REMAINS THE GOLD STANDARD FOR DIAGNOSIS - HISTOPATHOLOGICALLY, THERE IS A COLLECTION OF YELLOWISH-BROWN (OCHRONOTIC) BANANA-SHAPED GLOBULES IN THE PAPILLARY DERMIS - HOMOGENOUS, EDEMATOUS DERMAL COLLAGEN ALSO MAY BE SEEN - EARLY STAGES MAY BE CLINICALLY INDISTINGUISHABLE FROM MELASMA, ESPECIALLY IN ASIANS - WITHOUT CESSATION OF OFFENDING AGENT, EXOGENOUS OCHRONOSIS IS PROGRESSIVE  MANAGEMENT: - TREATMENT IS RARELY HELPFUL - STOP THE OFFENDING DRUG TO PREVENT PROGRESSION - BROAD-SPECTRUM SUNSCREEN & SUN AVOIDANCE ARE IMPORTANT - TOPICAL RETINOIDS, ∝ - HYDROXY ACIDS, CORTICOSTEROIDS, & PHYSICAL THERAPIES SUCH AS CHEMICAL PEELS & QUALITY SWITCHED LASERS HAVE BEEN REPORTED IN THE TREATMENT BUT THERE HAS BEEN NO UNIVERSALLY EFFICACIOUS TREATMENT DOCUMENTED  POST INFLAMMATORY HYPERPIGMENTATION – - BROWNISH DISCOLORATION FROM THE ACCUMULATION OF IRON AND MELANIN PIGMENTS IN THE DERMIS - OCCURS AFTER FRICTION, TRAUMA, INFLAMMATORY DERMATOSES / ECZEMA SUCH AS ACNE ,ATOPIC ECZEMA, OR LICHEN PLANUS - SOME MEDICATIONS MAY DARKEN PIH -ANTIMALARIAL DRUGS -TETRACYCLINES - ANTICANCER DRUGS SUCH AS BLEOMYCIN, 5-FU, DOXORUBICIN - USUALLY RESOLVES AFTER TREATMENT OF UNDERLYING CAUSES THOUGH SLOW SPONTANEOUS IMPROVEMENT CAN BE EXPECTED POST INFLAMMATORY HYPERPIGMENTATION  SOLAR LENTIGENS - AGE SPOTS / ACTINIC LENTIGENS - BENIGN, BROWNISH PIGMENTED MACULES IN ADULTS ESPECIALLY INDIVIDUALS WITH FAIR SKIN WHO EASILY BURN AND TAN POORLY -ARISE IN MIDDLE AGE AND ALSO RESULT FROM SUN DAMAGE (AGE SPOTS) - MOST OFTEN FOUND IN THE FACE AND HANDS AND ARE LARGER MORE DEFINED THAN FRECKLES - TEND TO PERSIST FOR LONGER PERIODS AND DOES NOT DISAPPEAR DURING WINTER SOLAR LENTIGENS  TREATMENT: -EDUCATE PATIENT TO LIMIT SUN EXPOSURE - SUNSCREEN USAGE MUST HAVE HIGH SPF FACTOR (SPF 50),GOOD BROAD SPECTRUM COVER AGAINST ULTRAVIOLET RADIATION (UVA), AND SHOULD BE APPLIED LIBERALLY AND FREQUENTLY TOPICAL TREATMENTS: - HYDROQUINONE -AZELAIC ACID -TRETINOIN -GLYCOLIC ACID (∞∞ HYDROXYL ACIDS)  -KOJIC ACID -ARBUTIN -LICORICE -NIACINAMIDE CHEMICAL PEELS LASER TREATMENT MULTIPLE SESSIONS IPL CRYOTHERAPY  PITYRIASIS ALBA - PITYRIASIS SIMPLEX - ERYTHEMA STREPTOGENES - HYPOPIGMENTED, ROUND, SCALY PATCHES IN THE FACE, UPPER ARMS, NECK OR SHOULDERS - ASYMPTOMATIC - OCCUR CHIEFLY IN CHILDREN AND TEENAGERS - UNKNOWN ETIOLOGY THOUGH THOUGHT TO BE DUE TO EXCESSIVE DRY SKIN FOLLOWING EXPOSURE TO STRONG SUNLIGHT - PROGNOSIS IS GOOD WITH SPONTANEOUS HEALING W/IN SEVERAL WEEKS  VITILIGO – ACQUIRED DEPIGMENTED WHITE PATCHES ( LACK MELANOCYTES) - COMMONLY AFFECTS THE FACE, UPPER PART OF THE CHEST, DORSAL ASPECTS OF THE HANDS, KNEES , AXILLAE, GROIN, EYES, NOSE MOUTH, EARS, NIPPLES, UMBILICUS, PENIS AND CLITORIS. - AFFECTS BOTH SEXES AND ALL RACES - WHITE PATCHES ARE HYPERSENSITIVE TO UV LIGHT AND BURNS READILY WHEN EXPOSED TO SUN - ASSOCIATED WITH DM, PERNICIOUS ANEMIA, BILIARY CIRRHOSIS AND ACROMEGALY - 4 POSSIBLE CAUSES ARE: A. AUTOIMMUNITY C. EXOGENOUS CHEMICAL EXPOSURE B. NEUROHUMORAL FACTORS D. AUTOTOXICITY - DISTAL EXTREMITIES, LIPS AND SEGMENTED LESIONS ARE LEAST RESPONSIVE TO TREATMENT  - TREAT WITH PUVA -.1& TOPICAL PSORALEN SOLUTION IS THE PREFERED TREATMENT FOR CHILDREN - PSORALEN THERAPY IS CONTRAINDICATED IN PERSONS WITH CONCOMITANT LIVER DISEASE, PORPHYRIA AND SLE - MAY GIVE TRIAMCINOLONE ACETONIDE INJECTIONS AND TOPICAL CORTICOSTEROIDS PROGNOSIS FOR VITILIGO: FAIR – FACE / NECK / CHEST / UPPER ARMS / LEGS AND IN COLOURED RACES BAD – WIDESPREAD / CAUCASIANS / MUCOSAE / FINGERS / LIPS / TOES / PALMS