Hair and Nail Disorders

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Non-Cicatricial Alopecias - Hair Today Gone Tomorrow

Clinical images of hair and nail disorders

FeatureAndrogenetic Alopecia (AGA)Alopecia Areata (AA)Telogen Effluvium (TE)
Key FeaturesGradual, patterned loss (Hamilton-Norwood/Ludwig); follicular miniaturizationAutoimmune; patchy/total loss (ophiasis); nail pitting; exclamation mark hairsAcute, diffuse shedding 2-3 months post-trigger; +ve pull test
Histology↑Telogen hairs, miniaturized follicles, ↓anagen:telogen ratioPeribulbar lymphocytic infiltrate ("swarm of bees")↑Telogen hairs (>20-25%); no significant inflammation
Treatment PearlsMinoxidil, Finasteride (males), Spironolactone (females)Corticosteroids (topical/IL/systemic), immunotherapyAddress trigger, reassurance, topical Minoxidil

Cicatricial Alopecias & Hair Shaft - Scarred Scalps Snapped Strands

Permanent hair loss due to follicle destruction and scarring. Key types:

FeatureLichen Planopilaris (LPP)DLE (Scalp)Folliculitis Decalvans (FD)
ClinicalPerifollicular erythema/scaling. Frontal Fibrosing Alopecia (FFA) variant.Erythematous plaques, atrophy, follicular plugging, dyspigmentation.Chronic pustules, crusts. 'Tufted folliculitis' (polytrichia).
HistologyLymphocytic interface/bulge infiltrate, perifollicular lamellar fibrosis, vacuolar alteration. Loss of sebaceous glands.Epidermal atrophy, follicular plugging, interface dermatitis, thickened basement membrane, dermal mucin.Early: neutrophilic perifollicular abscess. Late: lymphoplasmacytic infiltrate, plasma cells, fibrosis.
DistinguishingLonely hairs, loss of follicular openings.Carpet tack sign. Photosensitivity.Often S. aureus. Boggy, tender scalp.

⭐ 'Tufted folliculitis' is characteristic of Folliculitis Decalvans.

Hair shaft defects (e.g., Trichorrhexis Nodosa) cause brittle hair, snapped strands, usually non-scarring.

Nail Infections & Anatomy - Fungal Fingers Toe Troubles

Anatomy of the nail unit and paronychia)

  • Nail Anatomy: Plate, bed, matrix (growth), nail folds (proximal/lateral), eponychium (cuticle), hyponychium.
  • Onychomycosis (Tinea Unguium): Fungal nail infection.
    TypeOrganism(s) HighlightsKey Feature(s)
    DLSOT. rubrum (most common)Distal/lateral entry, subungual hyperkeratosis
    WSOT. mentagrophytesSuperficial white patches on nail plate
    PSOT. rubrum, Candida (HIV assoc.)Proximal entry, cuticle; immunocompromised
    TDOEnd-stage of othersTotal nail destruction, thickened
  • Paronychia: Nail fold inflammation.
    • Acute: Bacterial (S. aureus, Strep.). <6 wks. Rapid pain, erythema, pus. Tx: Warm soaks, antibiotics.
    • Chronic: Candida albicans, irritants. >6 wks. Boggy, tender folds, nail dystrophy. Tx: Avoid irritants, antifungals.

Trichophyton rubrum is the most common dermatophyte causing onychomycosis worldwide.

Nail Disease & Tumors - Nail Clues Nasty Knots

  • Nail Psoriasis vs. Lichen Planus (LP):

    FeaturePsoriasisLichen Planus (LP)
    PittingIrregular, deepFine, rare
    OnycholysisCommon, "oil drop"Common
    Subungual HyperkeratosisCommonCommon
    PterygiumAbsentPresent (dorsal, classic)
    Nail Psoriasis Manifestations
  • Key Nail Lines & Associations:

    • Beau's lines: Transverse grooves; severe illness, chemo. Beau's lines on fingernails
    • Mees' lines: Transverse white bands; arsenic, renal failure.
    • Muehrcke's lines: Paired white bands (nail bed); hypoalbuminemia.
  • Other Important Changes:

    • Clubbing: Lovibond angle >180°; lung disease, cyanotic heart disease. Clubbing: Grading, Causes, and Mnemonic
    • Koilonychia: Spoon nails; iron deficiency.
    • Onycholysis: Nail plate separation from bed.
    • Paronychia: Nail fold inflammation (acute/chronic).
    • Onychomycosis: Fungal; thick, discolored.
  • Melanonychia Evaluation: (📌 ABCDEF rule for melanoma)

> ⭐ Hutchinson's sign (pigment on proximal/lateral nail fold) is a red flag for subungual melanoma. ![Hutchinson's sign in subungual melanoma](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Pathology_Dermatopathology_Hair_and_Nail_Disorders/d323ac8e-1252-4abd-9248-428a6f9f3598.jpg)
  • Nail Tumors:
    • Glomus tumor: TRIAD - severe pain, cold sensitivity, localized tenderness. Bluish.
    • Subungual melanoma: Often melanonychia; check Hutchinson's sign.

High‑Yield Points - ⚡ Biggest Takeaways

  • Alopecia Areata: Peribulbar lymphocytic infiltrate ("swarm of bees") is characteristic.
  • Androgenetic Alopecia: Shows hair follicle miniaturization and ↑ telogen hairs.
  • Lichen Planopilaris: Follicular interface dermatitis and fibrosis cause scarring alopecia.
  • Tinea Capitis: Fungal elements (endothrix/ectothrix) in hair; PAS stain confirms.
  • Nail Psoriasis: Oil spots, pitting, onycholysis; neutrophils in nail plate (Munro's).
  • Onychomycosis: Fungal hyphae in nail plate/bed; PAS stain is diagnostic.
  • DLE: May cause scarring alopecia with follicular plugging, interface changes.

Practice Questions: Hair and Nail Disorders

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All are nail changes seen in cases of psoriasis except:

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Flashcards: Hair and Nail Disorders

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_____ may be associated with Munro microabscesses, which are collections of neutrophils in the stratum corneum

TAP TO REVEAL ANSWER

_____ may be associated with Munro microabscesses, which are collections of neutrophils in the stratum corneum

Psoriasis

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