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Cicatricial (Scarring) Alopecia — 10-Mark Answer (3rd Year Dermatology PG Theory)

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INTRODUCTION (1 mark)

• Permanent, irreversible destruction of hair follicles
• Replacement of follicular epithelium by fibrous tissue
• Clinical hallmark: loss of follicular ostia on examination/trichoscopy
• Histological hallmark: follicular replacement by fibrous tracts

1. Primary — follicle is the primary target of inflammation
2. Secondary — follicle is an "innocent bystander" (burns, radiation, morphea, cutaneous TB, malignancy)

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CLASSIFICATION — North American Hair Research Society (NAHRS) (1 mark)

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LYMPHOCYTIC GROUP (3 marks)

1. Lichen Planopilaris (LPP)

• Epidemiology: Most common primary cicatricial alopecia; predominantly White women, 40–60 years
• Pathogenesis: Immune-mediated CD8+ T-lymphocytic attack on the infundibulo-isthmic (bulge) region; associated with PPARγ dysfunction
• Clinical features:
  • Perifollicular erythema and keratotic scaling (perifollicular hyperkeratosis) — pathognomonic
  • Burning, pruritus, pain as premonitory symptoms
  • Patchy cicatricial alopecia; "lonely hairs" in burned-out lesions
  • Up to 15% have concurrent mucosal lichen planus
• Trichoscopy: Perifollicular scaling with tubular hair casts extending 2–3 mm above scalp; loss of follicular openings; milky-red areas (end-stage)
• Histology: Lichenoid (band-like) lymphocytic infiltrate at isthmus/infundibulum; vacuolar degeneration of basal layer; perifollicular fibrosis; loss of sebaceous glands
• Treatment: Hydroxychloroquine, doxycycline, intralesional/oral corticosteroids; JAK inhibitors, pioglitazone (second-line)

2. Frontal Fibrosing Alopecia (FFA)

• Epidemiology: Predominantly perimenopausal women; incidence rising globally
• Pathogenesis: LPP-spectrum disease; CD8+ lymphocytic infiltrate at bulge; environmental triggers (leave-on cosmetics, sunscreens) implicated
• Clinical features:
  • Band-like recession of frontotemporal hairline (0.3–1.5 mm/month progression)
  • Eyebrow loss (in up to 80%) — often the first sign
  • Facial papules over cheeks/forehead (perifollicular facial papules)
  • Three patterns: linear, diffuse, pseudo-fringe
  • Occipital and retro-auricular hairlines may also be involved
• Trichoscopy: Perifollicular scaling, "lonely hairs," loss of follicular openings at margin
• Histology: Identical to LPP — lymphocytic infiltrate at isthmus, follicular fibrosis
• Treatment: 5α-reductase inhibitors (finasteride/dutasteride) — may halt progression; hydroxychloroquine, intralesional steroids; JAK inhibitors

3. Discoid Lupus Erythematosus (DLE)

• Epidemiology: Most common cause of scarring alopecia alongside LPP; females > males; onset 20–40 years
• Clinical features:
  • Erythematous, atrophic, depigmented patches with follicular plugging
  • Hyperpigmentation centrally, hypopigmentation at edges
  • Telangiectasia and scarring
  • "Carpet-tack" sign — adherent scales with follicular plugging
  • Active lesions: pruritus/pain; worsen with UV exposure
  • 5–10% adults and 26–31% children may develop systemic SLE
• Histology: Interface dermatitis with vacuolar degeneration of basal layer; thickened basement membrane; lymphocytic infiltrate around follicles AND perivascular; periadnexal; destruction of elastic fibers; mucin deposition
• DIF: Linear granular deposition of IgG and C3 at the DEJ (positive lupus band test)
• Treatment: Hydroxychloroquine (200–400 mg/day); intralesional triamcinolone acetonide 10 mg/mL; topical class I steroids; sunscreen; acitretin (second-line)

4. Pseudopelade of Brocq (PPB)

• Features: Slowly progressive, painless cicatricial alopecia; "footprints in the snow" appearance — irregular, discrete, confluent alopecic patches with no signs of inflammation
• Trichoscopy: Milky-red areas, sparse terminal hairs, no inflammatory features
• Histology: Minimal inflammation; perifollicular fibrosis replacing the follicle; considered an end-stage pattern by some

5. Central Centrifugal Cicatricial Alopecia (CCCA)

• Epidemiology: Predominantly Black women; most common cicatricial alopecia in women of African descent; some cases linked to PADI3 mutations (encodes peptidyl arginine deiminase type III)
• Clinical features:
  • Begins at vertex/mid-scalp, expands centrifugally outward
  • Mild episodic pruritus or tenderness
  • Isolated tufts/hairs stranded in scarred areas
  • Associated with traumatic hair practices (traction, hot-combing) — though unproven causally
• Trichoscopy: Peripilar white/grey halos, broken hairs, perifollicular scaling; loss of follicular openings
• Histology: Premature desquamation of the inner root sheath; perifollicular lymphocytic infiltrate
• Treatment: Intralesional/topical corticosteroids, oral tetracyclines, immunosuppressants; cessation of traumatic hair practices

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NEUTROPHILIC GROUP (2 marks)

6. Folliculitis Decalvans (FD)

• Epidemiology: ~11% of all primary cicatricial alopecias; young/middle-aged adults; slight male predominance
• Pathogenesis: Staphylococcus aureus colonization with superantigen hypersensitivity + defective host cell-mediated immunity → recurrent follicular infection and scarring
• Clinical features:
  • Starts at vertex with erythematous patches, follicular pustules, and hyperkeratosis
  • Tufted folliculitis — pathognomonic: 5–15 hairs emerging from a single dilated follicular orifice
  • Pain, itching, burning sensations
  • Progressive scarring even after pustules resolve
• Histology: Early: keratin aggregation in infundibulum + neutrophilic infiltrate (intra- and perifollicular); sebaceous glands destroyed early; Later: lymphocytes, plasma cells, hair-shaft granulomas with foreign-body giant cells; end-stage: dermal fibrosis
• Treatment: Bacterial culture + sensitivity; rifampicin + clindamycin combination (most effective); minocycline, erythromycin; intralesional triamcinolone; intranasal mupirocin for S. aureus decolonization; prolonged/relapsing treatment often required

7. Dissecting Folliculitis / Dissecting Cellulitis (Perifolliculitis Capitis Abscedens et Suffodiens of Hoffmann)

• Part of the "follicular occlusion tetrad": acne conglobata + hidradenitis suppurativa + pilonidal sinus + dissecting cellulitis
• Epidemiology: Young Black males predominantly; androgen-driven
• Pathogenesis: Follicular occlusion → rupture → abscess formation → dissecting tracts
• Clinical features:
  • Boggy, fluctuant, painful nodules and abscesses on the scalp
  • Intercommunicating sinus tracts — diagnostic hallmark
  • Purulent discharge from multiple openings
  • Leads to severe scarring; may be associated with spondylarthropathy
• Histology: Perifollicular neutrophilic abscesses; disrupted follicles; granulomatous reaction; fibrosis
• Treatment: Isotretinoin (drug of choice — 0.5–1 mg/kg/day); rifampicin + clindamycin; TNF-α inhibitors (adalimumab); incision and drainage for fluctuant abscesses; excision of chronic lesions

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MIXED GROUP (1 mark)

8. Acne Keloidalis Nuchae (AKN)

• Epidemiology: Young Black males; occipital scalp/nape of neck
• Pathogenesis: Chronic folliculitis + ingrown hairs → keloid-like fibrosis; androgenic influence
• Clinical features:
  • Keloidal papules and plaques on the occiput and nape of neck
  • Pustular folliculitis → coalescent plaques → transverse keloidal scars
  • Tufted folliculitis can coexist
• Histology: Mixed lymphocytic and neutrophilic infiltrate; follicular rupture; foreign-body granulomas; progressive fibrosis and keloid formation
• Treatment: Potent topical steroids, intralesional triamcinolone; antibiotics (tetracyclines, clindamycin); laser (Nd:YAG); surgical excision for large plaques

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DIAGNOSIS — GENERAL APPROACH (1 mark)

Key biopsy principle: Sample the active, inflamed margin — not the burned-out center (which shows only end-stage fibrosis)

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TREATMENT SUMMARY (1 mark)

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KEY POINTS TO REMEMBER

1. Primary cicatricial alopecia targets the follicular bulge (isthmus); secondary is a bystander effect
2. NAHRS classification divides into lymphocytic, neutrophilic, mixed, and nonspecific
3. LPP + DLE = the two most common causes
4. Tufted folliculitis = hallmark of folliculitis decalvans
5. PCAS (Hoffman disease) = part of follicular occlusion tetrad
6. CCCA = most common cicatricial alopecia in Black women; PADI3 mutations
7. FFA = LPP variant; rising incidence; eyebrow loss + frontotemporal band recession
8. Biopsy from active margin is critical for diagnosis
9. DIF essential in DLE (lupus band)
10. Once destroyed, follicles cannot regenerate — early diagnosis and treatment are imperative

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Diagnostic Criteria for Neurofibromatosis and Pyoderma Gangrenosum

10-Mark Theory Answer — 3rd Year Dermatology Postgraduate Examination

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PART A: NEUROFIBROMATOSIS (5 marks)

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NEUROFIBROMATOSIS TYPE 1 (NF1) — 2021 Revised Diagnostic Criteria

Diagnosis requires ≥ 2 of the following criteria (in the absence of another diagnosis):

Key 2021 Revision Updates: (i) Choroidal abnormalities added alongside Lisch nodules; (ii) Pathogenic NF1 variant (molecular genetic testing) added as a standalone criterion; (iii) Mosaic NF1 criteria formalized separately.

Clinical Features of Individual Criteria:

• Most common first sign; present at birth or early infancy
• Uniform pigmentation without hair; hyperpigmented not hyperpigmented skin

• 90% of NF1 patients have ≥6 CALMs

• Single CALM in isolation is non-diagnostic (seen in 10–20% of normal population)

• Cutaneous neurofibromas: soft, pedunculated/sessile; "buttonholing" sign (finger invaginates on pressure); violaceous hue; appear post-puberty, increase with age and pregnancy
• Subcutaneous neurofibromas: firm, arise from peripheral nerves; "beaded necklace" in neck
• Plexiform neurofibromas: pathognomonic for NF1; large, bag-of-worms consistency; overlie a giant CALM with hypertrichosis; risk of malignant transformation to MPNST (~8–13% lifetime risk)

• Appears by 3–5 years
• Multiple small (<3 mm) tan macules; more specific than CALMs alone

• Melanocytic hamartomas of the iris stroma
• Seen on slit-lamp examination; asymptomatic
• Present in >94% of adults with NF1; age-dependent penetrance

• Present in ~15% of children; often asymptomatic
• May cause visual loss, proptosis, precocious puberty
• Baseline ophthalmological surveillance is mandatory

• Sphenoid wing dysplasia → pulsating exophthalmos
• Tibial pseudarthrosis → anterolateral bowing → pathological fractures
• Scoliosis (dystrophic or non-dystrophic), osteoporosis

Other NF1 Associations:

• Learning disabilities (~50%)
• Cardiovascular: renal artery stenosis, hypertension, pulmonary stenosis
• CNS tumors (gliomas, astrocytomas)
• UBOs (Unidentified Bright Objects on MRI T2) — foci of increased signal intensity
• Juvenile xanthogranuloma + NF1 = risk of juvenile chronic myelogenous leukemia

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NEUROFIBROMATOSIS TYPE 2 (NF2) — Diagnostic Criteria

Diagnosis requires ONE of the following (Manchester Criteria):

• Presents in adulthood (mean onset ~20s) with bilateral sensorineural hearing loss, tinnitus, vertigo
• Cutaneous features: cutaneous schwannomas (plaque-like, slightly raised, violaceous hue ± hair) — characteristic; fewer CALMs (<6); no axillary freckling; no Lisch nodules
• Juvenile posterior subcapsular cataracts (60–80%)
• Multiple meningiomas, spinal ependymomas, cranial nerve schwannomas
• Greater morbidity than NF1 — paralysis and deafness common
• Earlier onset = greater severity

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PART B: PYODERMA GANGRENOSUM (5 marks)

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CLINICAL VARIANTS OF PG

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THREE MAJOR DIAGNOSTIC CRITERIA SYSTEMS

1. Su Criteria (2004)

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2. PARACELSUS Score

Score > 10 = Highly likely PG

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3. Delphi Consensus Criteria (Maverakis et al., 2018) — Currently Most Widely Used

Note: All criteria are best applied to untreated disease — not disease partially treated by immunosuppressants.

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HISTOPATHOLOGY OF PG

Key biopsy principle: PG is a diagnosis of exclusion — there are NO pathognomonic histologic features; histology rules out other causes (infection, vasculitis, malignancy)

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INVESTIGATION PROTOCOL FOR PG

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ASSOCIATED DISEASES (50% of PG cases)

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TREATMENT OF PG (Brief)

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KEY EXAM MNEMONICS

• CAFé-au-lait macules (≥6)
• Axillary/inguinal freckling
• Family history (1st degree)
• Extra osseous lesions (sphenoid, tibia)
• Plexiform neurofibroma (or ≥2 neurofibromas)
• Optic glioma
• + Lisch nodules (≥2)
• + Pathogenic NF1 gene variant (2021 addition)

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