Pigmentation disorders Notes

NOTES NOTES PIGMENTATION DISORDERS GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Skin loses pigment, becomes lighter/darker ▪ Pigment-producing cells (melanocytes) ▫ Expected number, overproduce pigment (melanin) ▫ Higher in number, produce expected melanin ▫ Destroyed, no melanin produced DIAGNOSIS LAB RESULTS ▪ Skin biopsy ▪ Genetic testing OTHER DIAGNOSTICS ▪ Dermatological physical examination (e.g. dermoscopy) CAUSES ▪ Autoimmune disorders → melanocyte destruction ▪ Long periods of sun exposure ▪ Genetic mutations SIGNS & SYMPTOMS ▪ Changes in skin pigmentation only symptom ▪ Some disorders (esp. produced by sun overexposure) heighten risk of skin cancer TREATMENT ▪ Usually no cure MEDICATIONS ▪ Topical medication ▫ Most respond to steroids ▫ Depigmentation agents effective for hyperpigmentation disorders SURGERY ▪ For some lesions OTHER INTERVENTIONS ▪ Sun avoidance, if caused by ultraviolet (UV) overexposure 38 OSMOSIS.ORG

Chapter 7 Pigmentation Disorders ALBINISM osms.it/albinism PATHOLOGY & CAUSES SIGNS & SYMPTOMS ▪ Congenital condition; skin, eyes, hair partially (hypomelanistic albinism)/ completely (amelanistic albinism) devoid of pigment ▪ Lack of pigment → dermatological problems ▫ Increased risk of sunburn, skin cancer ▪ Complete/partial absence of skin pigmentation ▪ Light yellow/white hair ▪ Light eye colour ▫ Light blue (partial pigment production) ▫ Pink (complete absence of pigment production) ▪ Visual problems ▫ Visual development in fetus highly dependent on melanin production; abnormal arrangements in optic nerves fibres (e.g. abnormal optic chiasm) ▫ Severe sensitivity to light ▫ Poor visual acuity due to foveal hypoplasia ▫ Amblyopia/nystagmus: poor coordination between eye, brain TYPES Oculocutaneous albinism (OCA) ▪ Eyes, skin; possibly hair ▪ Autosomal recessive transmission ▪ Seven different subtypes; OCA1, OCA2 most common ▫ OCA1: defect in gene for enzyme tyrosinase (TYR) ▫ OCA2: defect in P gene (membrane transporter, moves amino acid tyrosine) ▪ Rufous oculocutaneous albinism ▫ Specific subtype of OCA ▫ Common in people of sub-Saharan African descent Ocular albinism (OA) ▪ Only eyes ▪ OA1 most common subtype (AKA Nettleship–Falls syndrome) ▫ X-linked recessive inheritance ▫ Lack of pigment in retinal epithelium DIAGNOSIS LAB RESULTS ▪ Genetic testing ▫ Identify defective gene, allotype OTHER DIAGNOSTICS ▪ Physical examination ▪ Family history CAUSES ▪ Hereditary/genetic ▫ Autosomal/X-linked ▫ Recessive inheritance pattern → defect leading to lack/absence of enzyme in melanin synthesis pathway → hypopigmentation/depigmentation ▪ Chediak–Higashi syndrome ▫ Rare; malfunctions in lysosomal trafficking regulator gene (CHS1/LYST) OSMOSIS.ORG 39

TREATMENT ▪ No cure SURGERY ▪ Manage strabismus, nystagmus OTHER INTERVENTIONS ▪ Lifestyle management ▫ Avoid sunburn ▫ Regular dermatological, ophthalmological check-ups ▫ Visual rehabilitation ▫ Glasses/contact lenses Figure 7.1 A baby with albinism. PITYRIASIS ALBA osms.it/pityriasis-alba PATHOLOGY & CAUSES ▪ Common, irregularly hypopigmented skin condition: slightly scaly patches, macules ▫ Lesion diameter: 0.5–5cm/0.2–2in ▫ Irregular borders ▫ Most common on face, neck, shoulders, upper arms ▫ May resolve spontaneously after puberty CAUSES ▪ Unknown etiology: eczema-related postinflammatory hypopigmentation (possible relation) RISK FACTORS ▪ ▪ ▪ ▪ ▪ 40 OSMOSIS.ORG Atopy Sun exposure Frequent bathing Biologically male Children/adolescents > adults COMPLICATIONS ▪ Benign condition SIGNS & SYMPTOMS ▪ Often asymptomatic, may itch/burn DIAGNOSIS OTHER DIAGNOSTICS ▪ Wood’s lamp examination: hypomelanosis patches ▪ Microscopy: ↓ melanocyte number, size TREATMENT MEDICATIONS ▪ Hydrocortisone (topical), calcineurin inhibitors, emollients

Chapter 7 Pigmentation Disorders VITILIGO osms.it/vitiligo PATHOLOGY & CAUSES ▪ Pigmentation disorder; parts of skin, hair lose pigment ▪ Melanocytes destroyed → white patches of depigmented skin ▫ Sharp margins on depigmented patches ▪ May be autoimmune condition SIGNS & SYMPTOMS ▪ Depigmented skin patches only symptom, usually on extremities ▪ Patches grow over time (non-segmental subtype) ▪ Can be associated with alopecia DIAGNOSIS TYPES Segmental ▪ Areas innervated by dorsal roots of spinal cord ▪ Unilateral; stable over time Non-segmental ▪ Symmetrical; appearance of new patches ▪ Multiple subtypes ▫ Vitiligo universalis: most severe, almost no pigmented skin remains ▫ Generalized: most common ▫ Focal: smaller, localised patches ▫ Acrofacial: hands, face ▫ Mucosal: only mucous membranes CAUSES ▪ Autoimmune disorder → melanocyte destruction RISK FACTORS ▪ Medical/family history of autoimmune conditions ▫ Hashimoto’s thyroiditis ▫ Type I diabetes mellitus ▫ Systemic lupus erythematosus ▫ Celiac disease ▫ Addison’s disease ▪ Rule out autoimmune/inflammatory disorders OTHER DIAGNOSTICS ▪ Ultraviolet light (Wood’s lamp): lesions; vitiligo turns blue TREATMENT ▪ No cure MEDICATIONS ▪ Topical immune system suppressing medication ▪ Glucocorticoids ▪ Calcineurin inhibitors OTHER INTERVENTIONS ▪ Ultraviolet light therapy (phototherapy) ▪ Skin camouflage (e.g. makeup) OSMOSIS.ORG 41

Figure 7.2 The clinical appearance of vitiligo affecting the hands. 42 OSMOSIS.ORG