Part I. Clinical picture, histopa
Abdullah Alkhalifah, MD,a Adel Alsantali, MD,a
and Jerry ShapVancouver, British Columbia, Cana
Alopecia areata (AA) is an autoimmune disease that preDisease prevalence rates from 0.1% to 0.2% have beenhair-bearing area. It often presents as well demarcatednormal appearance. Recently, newer clinical variantsciated with a higher frequency of other autoimmuneed psychiatric morbidity in patients with AA. Althoughns, the course of the disease is unpredictable and theof this two-part series on AA describes the clinicalture. It also proposes a hypothesis for AA developmentthogenesis. ( J Am Acad Dermatol 2010;62:177-88.)
g activity, participants should be familiar with the mostrare and recently described variants of AA, and be ableges of AA.
AAcases, and as many as 60% of patients with AA willa0190-9622/$36.00
d AA classically presents as asymptomatic,well defined patches of nonscarring alopeciawith no overt epidermal changes
2009 by the American Academy of Dermatology, Inc.doi:10.1016/j.jaad.2009.10.032present with their first patch before 20 years of age.9
One study suggests that 85.5%ofAsianpatientswithAAhave disease onset before 40 years of age.2 The diseaseprevalence peaks between the second and fourthdecades of life.10
From the Department of Dermatology and Skin Science, Univer-
sity of British Columbia, Vancouver, and the Department of
Dermatology,b New York University.
Funding sources: None.
Conflicts of interest: Dr Shapiro is a consultant for Johnson and
Johnson Inc. Drs Shapiro and McElwee are cofounders of
TrichoScience Innovations Inc. The other authors, editors, and
peer reviewers have no relevant financial relationships.
Reprint requests: Jerry Shapiro, MD, University of British Columbia
Skin Care Center, 835 W 10th Ave, Vancouver, BC, V5Z 4E8,
Canada. E-mail: firstname.lastname@example.org areata (AA) occurs in populationsworldwide.a common disease encountered by dermatologists,a frequency ranging from 0.7% to 3.8% of patients
nding dermatology clinics.1,2 In the United States,as estimated tooccur in0.1% to0.2%of thegeneralulation,3 with a lifetime risk of 1.7%.4 Overall, AAly affects males and females equally.5 Some studiesa significantmale preponderance in the adult agep, although others identify contrasting results.6,7
Pediatric AA constitutes approximately 20% of8
AT: alopecia totalisAU: alopecia universalisCD4/8: cluster of differentiation 4/8DEBR: Dundee experimental bald ratHLA: human leukocyte antigenHPA: hypothalamic-pituitary-adrenalMHC: major histocompatibility complexSCID: severe combined immunodeficientTE: telogen effluviumAlopMOGRAPHICSy pointlopecia areata affects all age groups and dif-rent ethnicities, with equal sex distribution
AA: alopecia areataAPC: antigen presenting cellAPS: autoimmune polyglandular syndromeKey words: alopecia areata; alopecia totalis; alopepathogenesis.cia universalis; nonscarring alopecia; pathology;pathogenesis of the disease remains to be clarified.estimated for the United States. AA can affect anypatches of nonscarring alopecia on skin of overtlyhave been described. The presence of AA is assodiseases. Controversially, there may also be increassome AA features are known poor prognostic sigresponse to treatment can be variable. Part onepresentation and the associated histopathologic picbased on the most recent knowledge of disease pa
Learning objectives: After completing this learninrecent advances in AA pathogenesis, recognize theto distinguish between different histopathologic staAL EDUCATION
thology, and pathogenesis
Eddy Wang, BSc,a Kevin J. McElwee, PhD,a
da, and New York, New York
sents as nonscarring hair loss, although the exact177
band-like hair loss inarea (Fig 4); and aor all of the scalp.e considered is acuteich was first describedd was reported morerger series of patientsis new variant is char-ession and extensiveorable prognosis.demarcated, round oroth-surfaced patchesatch is usually normalever, it is not uncom-(Fig 6) or reddened10
d Trichotillomania and tinea capitis are the
d Diffuse AA can btelogen effluvium
In children, the mosare tinea capitis and tcan be differentiated byor at least mild scaling.irregular or bizarrely shbroken hairs with varrough texture, unlike thdifferentiation of diffus(TE) can be challenginreveal a triggering factdiagnosis of TE. In diffshow some dystrophic
ic pstaclaso thist.
J AM ACAD DERMATOLFEBRUARY 2010
178 Alkhalifah et alcolor. A characteristic finding that is frequently seenin (or at the border of) the patches is exclamationmark hairs.5 These are short hairs that are taperedproximally and wider distally (Fig 7). In activedisease, where alopecia patches are expanding, ahair pull test may be positive at the periphery oflesions.11 An interesting feature of AA is its initialsparing of white hairs in patients with graying hair.10in parieto-temporo-occipitalinversus (sisapho), very rarethe fronto-parieto-temporaldiffuse thinning over partAnother variant that should bdiffuse and total alopecia, whby Sato-Kawamura et al14 anrecently by Lew et al15 in a lawith similar characteristics. Thacterized by its rapid progrinvolvement, along with a fav
Classic AA lesions are welloval, completely bald, smo(Fig 5).11 The skin within the pon the first examination; howmon to see a slightly peachy11d Patches can be mildly reddened or peachy incolor
d Acute diffuse and total alopecia is a newvariant of AA with favorable prognosis
AA can occur on virtually any hair-bearing area,but it affects the scalp in approximately 90% of casesseen in dermatology clinics.5 The disease can beclassified based on the extentor pattern of the hair loss.11,12
The hair loss can presentas single delimited patches ofhair loss (most common),multiple patches, or exten-sive hair loss. Based on theextent of hair loss, the dis-ease is clinically classified asfollows: patchy AA, in whichthere is a partial loss of scalphair (Fig 1); alopecia totalis(AT), in which 100% of scalphair is lost (Fig 2); or alopeciauniversalis (AU), in whichthere is a 100% loss of allscalp and body hair. Approximately 5% of cases willprogress to AT/AU.13
The pattern of hair loss observed in AA can varyconsiderably, and less common presentations can beobserved in a minority of patients, including reticularpatches of hair loss; ophiasis type, band-like hair loss
area (Fig 3); ophiasis
d Alopecia areata punderstood.
d A new variant offavorable prognodescribed.
d The histopathologdepending on thein the absence ofcan be puzzling tdermatopathologHowever, eventually white hair is also often lost aspure telogen hairs found in TE. Ultimately, a scalpbiopsy may be required to correctly differentiatediffuse AA and TE. Lupus and secondary syphilismay also be considered in the differential diagnosisof AA and may require serology testing or a scalpbiopsy for confirmation. Where a strong family asso-ciation of universal hair loss is observed, the differ-ential diagnosis may include a rare inherited genetic
hair loss condition callee easily misdiagnosed as
t important entities to rule outrichotillomania. Tinea capitisthe presence of inflammationTrichotillomania may involveaped lesions. The presence ofying lengths gives lesions ae smooth surface of AA. Thee AA from telogen effluviumg. The patients history mayor that may point towards ause AA, the hair pull test mayanagen hairs compared to themost important differential diagnoses inchildrenthe disease duration becomes chronic. Initial hairregrowth, whether spontaneous or induced by treat-ment, is typically non- or hypopigmented (Fig 8), butthe color usually returns with time.10 The disease isfrequently asymptomatic, although a few patientsreport pruritus, burning sensations, or pain beforehair loss begins.11
The use of videodermo-scopywith amagnification of20 to 70 times may be avaluable, noninvasive toolin equivocal AA cases. Thepresence of numerous yel-low dots and short regrowinghairs is suggested to be acharacteristic feature.16,17
Yellow dots, however, canalso be seen in androgenicalopecia.18 Close examina-tion of the hair shafts at theedge of lesions, particularlyexclamation mark hairs, mayreveal subtle defects in the
structure and cuticle.19
DIFFERENTIAL DIAGNOSISKey points
genesis is not fully
ecia areata with aas recently
icture variesge of disease and,sic inflammation, ite inexperiencedd congenital atrichia.20
J AM ACAD DERMATOLVOLUME 62, NUMBER 2
Alkhalifah et al 179Fig 1. Patchy alopecia areata in the right frontotemporalarea. Note eyebrow involvement.PROGNOSISKey pointsd The extent of AA involvement is probablythe most important prognostic factor
d In AT/AU, the chance of full recovery is lessthan 10%
The course of AA is unpredictable. Up to 50% ofpatients will recover within 1 year even withouttreatment.12 However, most patients will have morethan one episode of hair loss. The most importantfactors indicating a poor prognosis are the extent ofhair loss presentation (extensive AA/AT/AU)21 or anophiasis pattern of hair loss.15 Other factors associ-ated with a poor prognosis include a long duration ofhair loss,15 atopy, a positive family history, the pres-ence of other autoimmune diseases, nail involve-ment, and young age of first onset.11 In children, thedisease may have a tendency towards worsening withtime, even if the initial presentation was mild.21 InAT/AU, the chance of full recovery is less tha