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D38 Dermatology
Diseases of Hair Density
Toronto Notes 2019
DDx of Non-Scarring (Non-Cicatricial) Alopecia
• Autoimmune
• Alopecia areata
• Endocrine
• Hypothyroidism
• Androgens
• Micronutrient deficiencies
• Iron
• Zinc
• Toxins
• Heavy metals • Anticoagulants • Chemotherapy • Vitamin A
• Trauma to the hair follicle
• Trichotillomania
• ‘Corn-row’ braiding
• Other
• Syphilis
• Severe illness • Childbirth
Precipitants of Telogen Effluvium “SEND” hair follicles out of anagen and into telogen
Stress and Scalp disease (surgery) Endocrine (hypothyroidism, post-partum) Nutritional (iron and protein deficiency) Drugs (citretin, heparin, lithium, IFN, β-blockers, valproic acid, SSRIs)
Non-scarring alopecia: intact hair follicles on examgbiopsy not required (but may be helpful)
Scarring alopecia: absent hair follicles on examgbiopsy required
Alopecia Areata Subtypes
Alopecia totalis: loss of all scalp hair and eyebrows
Alopecia universalis: loss of all body hair
DDx of Scarring (Cicatricial) Alopecia
Developmental/Hereditary Disorders
• Aplasia cutis congenita
• Epidermal nevi
• Romberg’s syndrome
• Generalized follicular hamartoma Primary Causes
• Group 1: Lymphocytic • DLE
• Lichen planopilaris
• Central centrifugal cicatricial alopecia • Classic pseudopelade
• Group 2: Neutrophilic
• Folliculitis decalvans
• Dissecting scalp cellulitis
• Group 3: Mixed
• Acne keloidalis nuchae
Secondary Causes
• Infectious agents
• Bacterial (e.g. post-cellulitis)
• Fungal (e.g. kerion tinea capitis)
• Neoplasms (e.g. BCC, SCC, lymphomas, and metastatic tumours)
• Physical agents
• Mechanical trauma • Burns
• Radiotherapy
• Caustic chemicals
Management
• minoxidil(Rogaine®)solutionorfoamtoreducerateofloss/partialrestoration
• females:spironolactone(anti-androgeniceffects),cyproteroneacetate(Diane-35®) • males:finasteride(Propecia®)(5-α-reductaseinhibitor)1mg/d
• hairtransplant
Physical
• trichotillomania:impulse-controldisordercharacterizedbycompulsivehairpullingwithirregular patches of hair loss, and with remaining hairs broken at varying lengths
• traumatic(e.g.tight“corn-row”braidingofhair,wearingtightponytails,tighttyingofturbans)
TELOGEN EFFLUVIUM
Clinical Presentation
• uniformdecreaseinhairdensitysecondarytohairsleavingthegrowth(anagen)stageandenteringthe resting (telogen) stage of the cycle
Pathophysiology
• varietyofprecipitatingfactors(i.e.post-partum,psychologicalstress,majorillness) • hairlosstypicallyoccurs2-4moafterexposuretoprecipitant
• regrowthoccurswithinafewmonthsbutmaynotbecomplete
ANAGEN EFFLUVIUM Clinical Presentation
• hairlossduetoinsultofhairfollicleimpairingitsmitoticactivity(growthstage)
Pathophysiology
• precipitatedbychemotherapeuticagents(mostcommon),othermeds(bismuth,levodopa,colchicine, cyclosporine), exposure to chemicals (thallium, boron, arsenic)
• dose-dependenteffect
• hairloss7-14daftersinglepulseofchemotherapy;mostclinicallyapparentafter1-2mo • reversible effect; follicles resume normal mitotic activity few weeks after agent stopped
ALOPECIA AREATA
Clinical Presentation
• autoimmunedisordercharacterizedbypatchesofcompletehairlossoftenlocalizedtoscalp,butcan affect eyebrows, beard, eyelashes, etc.
• maybeassociatedwithdystrophicnailchanges–finestippling,pitting
• “exclamationmark”pattern(hairsfracturedandhavetaperedshafts,i.e.lookslike“!”)
• maybeassociatedwithperniciousanemia,vitiligo,thyroiddisease,Addison’sdisease
• spontaneous regrowth may occur within months of first attack (worse prognosis if young at age of onset
and extensive loss)
• frequentrecurrenceoftenprecipitatedbyemotionaldistress
• alopeciatotalis:completelossofhaironscalp
• alopeciauniversalis:completelossofscalphair,eyelashes,eyebrows,andbodyhair
Management
• excellentprognosisforlocalizeddisease
• topical corticosteroids and intralesional triamcinolone acetonide (corticosteroids) can be used for
isolated patches
• systemicimmunosuppressantsforrefractoryorextensivedisease • immunomodulatory (diphencyprone, anthralin)
Scarring (Cicatricial) Alopecia
Clinical Presentation
• irreversiblelossofhairfollicleswithfibrosis
Etiology
• physical: radiation, burns
• infections: fungal, bacterial, TB, leprosy, viral (HZV) • inflammatory
■ lichen planus (lichen planopilaris)
■ DLE (note that SLE can cause an alopecia unrelated to DLE lesions which are non-scarring) ■ morphea: “coup de sabre” with involvement of centre of scalp