Diseases of cutaneous appendages Nathan C. Walk, M.D.
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
Why is examination of hair so tough?... Equation with many variables. A + B + C = X
Epidermal appendages Pilosebaceous unit Hair follicle Sebaceous gland +/ +/- Apocrine gland Eccrine sweat gland
Hair follicle
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
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
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
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
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
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
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
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
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!
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
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
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
Telogen effluvium INCREASED terminal telogen and catagen hairs Normal # follicles at top (decreased d deep) Normal Terminal:vellus Streamers
Alopecia areata Peribulbar mononuclear inflammation INCREASED miniaturized hairs INCREASED telogen/catagen hairs Normal # follicles early, decreased late
Trichotillomania INCREASED telogen/catagen Pigmented casts Traumatized hair follicles Bizarre morphology Normal # follicles (may be decreased late)
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
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
Neutrophilic scarring alopecias Acne keloidalis nuchae Dissecting cellulitis
Scarring alopecias Scarring Lymphocytic Central centrifugal scarring alopecia Follicular degeneration syndrome Pseudopelade (not Brocq s) Folliculitis decalvans Tufted folliculitis Lichen planopilaris Lupus erythematosus
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
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
CCSA versus LPP CCSA Lichen planopilaris p Asymmetry of follicles Lymphs IN epidermis, follicular epithelium < 16 follicles > 16 follicles
CCSA Note a few lymphs in follicular epithelium. Medicine is a continuum.
LPP
Case 98
HSV folliculitis
Case 99 A
Case 99 B
Dermatophytes Endothrix Fungal folliculitis Invasion of hair shaft Ectothrix Confined to surface of hair shaft 3 major genera Epidermophyton Microsporum Trichophyton
Case 100
Pitysporum folliculitis
Case 101
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
Case 102 A & B
Trichotillomania
Case 103
Rosacea
Case 104
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
Case 105
Demodex Folliculitis
Case 106 A & B
Lichen planopilaris
Case 107
Central centrifugal scarring alopecia
Case 108
Alopecia areata
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