Overview FOCUS on the hair follicle Scalp biopsy Hair anatomy Hair cycle anagen, catagen, telogen Alopecias Provide a basic algorithm Handout hits hig

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Marcia Stanley
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1 Diseases of cutaneous appendages Nathan C. Walk, M.D.

2 Overview FOCUS on the hair follicle Scalp biopsy Hair anatomy Hair cycle anagen, catagen, telogen Alopecias Provide a basic algorithm Handout hits highlights hli h Slide Unknowns Rapid fire

3 Why is examination of hair so tough?... Equation with many variables. A + B + C = X

4 Epidermal appendages Pilosebaceous unit Hair follicle Sebaceous gland +/ +/- Apocrine gland Eccrine sweat gland

5 Hair follicle

6 Scalp biopsy Valuable tool in the diagnosis of hair loss Ideally, 2 deep 4 mm punch biopsy should be obtained from different sites Healthy skin Established lesion WITH inflammation 4mm punch = 12.6 mm 2 3mm punch = 7.07 mm 2 Using 4mm punch, averages T:V 7:1, with 12 follicular units Caucasians 35/5 (T:V) African Americans 20/3 (T:V) Korean 15/2 Telogen+Catagen Normal 0-15%, >20% definitely abnormal

8 Hair anatomy Hair follicles ces Found everywhere on the body, except palms and soles Formation Intimate association between epithelial buds and mesenchymal elements Hair follicles in scalp Grouped into follicular units 2-6 Terminal hairs + vellus hairs Sebaceous glands Arrector pili

11 Terminal hairs Hair anatomy Larger than vellus hairs Descend to fat Pigmented Hair shaft diameter is > thickness of IRS Vellus hairs Thin, short, non-pigmented Hair shaft diameter is <= thickness of IRS Indeterminate hairs Intermediate in size

14 Hair anatomy The hair follicle can be anatomically and functionally divided into 2 distinct segments Upper portion Stable, not affected by maturation/shedding Ostium Infundibulum dbuu Isthmus Lower portion Ati Actively involved di in hair hi growth Stem/suprabulbar region Bulb

16 Hair anatomy Transverse sectioning allows all layers of the anagen follicle to be easily identified suprabulbar zone) Starting from center out 1. Hair shaft Medulla (not consistently present in humans) Cortex Cuticle 2. Internal root sheath Cuticle Huxley s layer Henle s layer 3. External root sheath 4. Vitreous layer 5. Fibrous root sheath

18 Hair anatomy Changes as we ascend Adamson s fringe Nuclei dropout in IRS and hair shaft [IRS shows tricholemmal keratinization] At (about mid) Isthmus IRS abruptly desquamates results in separation between hair shaft and follicular wall ERS begins to cornify without formation of a granular cell layer (tricholemmal keratinization) Infundibulum (bounded inferiorly by sebaceous gland) ERS switches to epidermal type keratinization, WITH a granular layer

30 Hair cycle Hair growth cycle, whether terminal or vellus, is divided into three stages Active growth = anagen 2-7 years Involution = catagen 2-3 weeks Rest = telogen 100 days

32 Catagen hair anatomy At the end of anagen, catagen begins Hair matrix disappears, replaced by thin rim of epithelial cells surrounding the hair papilla Epithelium of lower follicle undergoes disintegration by apoptosis Vitreous layer markedly thickens Fibrous root sheath thickens As catagen progresses over 2-3 weeks, the hair papilla follows disintegrating epithelial column upwards into the dermis Papilla eventually comes to rest just below bulge As epithelial column moves upward, a collapsed fibrous root sheath is left behind stela or streamer Club hair begins to form

33 Telogen At the end of catagen and the beginning of telogen, the hair papilla is a condensed ball of spindle-shaped shaped cells within a scanty stroma Above papilla lies the secondary hair germ Epithelium has asterisk like appearance on cross section Below papilla lies the stela (collapsed fibrous root sheath) Above secondary hair germ, club hair is forming Progressive cornification over 3 month period, after which the hair is shed At end of telogen, shortly before or after club hair is shed, stem cells of the follicular bulge are activated and form a population of rapidly proliferating i epithelium These cells descend into the vacant and collapsed fibrous root sheath Thus begins formation of a new anagen hair!

43 Alopecias Classification [Difficult Great degree of overlap Some variants are initially non-scarring, but may become scarring with time] Scarring Lymphocytic Central centrifugal scarring alopecia Lichen planopilaris Lupus erythematosus Neutrophilic Acne keloidalis Dissecting cellulitis Non-scarring Androgenic alopecia Alopecia areata Trichotillomania/Traction alopecia Tellogen effluvium

44 Scalp biopsy in alopecia Evaluation 1.?4mm 2. Evenly spaced follicles? 3. Are most units 2-6 follicles w/ LARGE > small 4. >85% telogen 5. Do any follicles show distorted features 6. Inflammation? 1. At what level? 7. Fibrosis? 8. Total number of 1. Follicular structures 2. Terminal hairs 3. Vellus hairs Using 4mm punch, averages T:V Caucasians African Americans 7:1, with 12 follicular units 33/5 (T:V) 21/3 (T:V) Tellogen+Catagen Normal 0-15%, >20% definitely abnormal

45 Androgenic alopecia Variation in follicle size miniaturization i.e. increased number vellus hairs Normal # follicles at top (decreased deep) Increased number of telogen/catagen hairs NO inflammation

48 Telogen effluvium INCREASED terminal telogen and catagen hairs Normal # follicles at top (decreased d deep) Normal Terminal:vellus Streamers

55 Alopecia areata Peribulbar mononuclear inflammation INCREASED miniaturized hairs INCREASED telogen/catagen hairs Normal # follicles early, decreased late

59 Trichotillomania INCREASED telogen/catagen Pigmented casts Traumatized hair follicles Bizarre morphology Normal # follicles (may be decreased late)

62 Scarring alopecias Scarring Lymphocytic Central centrifugal scarring alopecia Lichen planopilaris Lupus erythematosus Neutrophilic Acne keloidalis Dissecting cellulitis Non-scarring Androgenic alopecia Alopecia areata Trichotillomania/Traction alopecia Telogen effluvium

63 Pathophysiology of scarring alopecias obviously varies. Inflammation in upper ½ of hair follicle is CRUCIAL to the development of permanent damage age Stem cells located at bulge Remember in alopecia areata, although there IS intense inflammation around the hair bulb. This leads to involution of follicle but not its permanent loss until very late

64 Neutrophilic scarring alopecias Acne keloidalis nuchae Dissecting cellulitis

69 Scarring alopecias Scarring Lymphocytic Central centrifugal scarring alopecia Follicular degeneration syndrome Pseudopelade (not Brocq s) Folliculitis decalvans Tufted folliculitis Lichen planopilaris Lupus erythematosus

70 Scarring alopecias Central centrifugal scarring alopecia Follicular l degeneration syndrome Pseudopelade (not Brocq s) Folliculitis decalvans Tufted folliculitis CCSA groups several variants of inflammatory, scarring alopecia. Difference between these variants may be due to racial differences or variability in immune responses. Have in common: Chronic and progressive, with eventual burn out. Centered on crown, vertex Progress symmetrically Show clinical and histologic evidence of inflammation in active peripheral zone

71 Scarring Lymphocytic Central centrifugal scarring alopecia Lymphocytic infiltrate infundibulum/isthmus + NO basal vacuolar change Eccentric epithelial atrophy + Onion skin fibrosis Premature desquamation of IRS Lichen planopilaris Lymphocytic infiltrate infundibulum/isthmus + basal vacuolar change Colloid bodies + Some interface changes away from follicles Onion skin fibrosis Lupus erythematosus INTERFACE dermatitis lots away from follicles + basal vacuolar change S+D perivascular lymphocytic infiltrate Interstitial mucin

72 CCSA versus LPP CCSA Lichen planopilaris p Asymmetry of follicles Lymphs IN epidermis, follicular epithelium < 16 follicles > 16 follicles

78 CCSA Note a few lymphs in follicular epithelium. Medicine is a continuum.

79 LPP

80 Case 98

84 HSV folliculitis

85 Case 99 A

90 Case 99 B

96 Dermatophytes Endothrix Fungal folliculitis Invasion of hair shaft Ectothrix Confined to surface of hair shaft 3 major genera Epidermophyton Microsporum Trichophyton

97 Case 100

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102 Pitysporum folliculitis

103 Case 101

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112 Hidradenitis suppurativa Follicular occlusion triad 1. Hidradenitis suppurativa 2. Dissecting cellulitis of the scalp 3. Acne conglobata Deep scarring folliculitides Presumed common pathogenesis of pore occlusion followed by bacterial infection Draining sinuses

113 Case 102 A & B

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122 Trichotillomania

123 Case 103

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129 Rosacea

130 Case 104

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138 Folliculitis keloidalis nuchae Aka Acne keloidalis nuchae Deep scarring foliculitides litid 1. Folliculitis keloidalis nuchae Folliculitis w/ rupture, liberation of hair shafts into dermis More severe scarring than #2 2. Folliculitis decalvans

139 Case 105

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144 Demodex Folliculitis

145 Case 106 A & B

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155 Lichen planopilaris

156 Case 107

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162 Central centrifugal scarring alopecia

163 Case 108

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169 Alopecia areata

170 Selected pictures for this lecture taken from: Leonard C. Sperling An Atlas of Hair Pathology with Clinical Correlations Phillip McKee, et al Pathology of the Skin

Hair Chemistry. Chapter 1. Hair Relaxers Science, Design, and Application www.alluredbooks.com

Hair Chemistry. Chapter 1. Hair Relaxers Science, Design, and Application www.alluredbooks.com Hair Relaxers Science, Design, and Application www.alluredbooks.com Chapter 1 Hair Chemistry We all know that the hair on our head is dead, but underneath the scalp, within the hair follicle, is a surprisingly