Bullous Pemphigoid

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Bullous Pemphigoid: Overview & Patho - Elder Itch & Attack

  • Autoimmune disease: large, tense subepidermal blisters.
  • Affects elderly (>60 yrs); often preceded by intense pruritus (📌 "Elder Itch").
  • Pathophysiology ("Attack"):
    • Autoantibodies (IgG, IgE) target hemidesmosome proteins:
      • BPAG1 (BP230) - intracellular.
      • BPAG2 (BP180/Type XVII collagen) - transmembrane.
    • Immune cascade: Complement activation → eosinophil/mast cell recruitment → protease release → split at lamina lucida of basement membrane zone.

⭐ Most common autoimmune blistering disease in the elderly.

Bullous Pemphigoid: Clinical Canvas - Tense Bubbles Appear

  • Onset: Typically elderly, >60 years.
  • Prodrome: Intense pruritus, often preceding skin lesions by weeks/months; may have urticarial plaques.
  • Lesions: Hallmark is tense, large bullae (1-4 cm) filled with clear or serosanguinous fluid.
    • Arise on erythematous, urticarial, or normal-appearing skin.
  • Distribution: Predilection for flexural areas (axillae, groin, abdomen, inner thighs), trunk, and limbs.
  • Mucosal Involvement: Oral lesions in 10-30% of cases; typically less severe and extensive than in Pemphigus Vulgaris.
  • Healing: Usually without scarring, but post-inflammatory hyperpigmentation is common. Bullous Pemphigoid clinical presentation

⭐ Nikolsky sign is typically negative, distinguishing it from Pemphigus Vulgaris where it's often positive (skin surface does not shear off easily when rubbed).

Bullous Pemphigoid: Diagnostic Deep Dive - Unmasking BP

  • Skin Biopsy (H&E): Subepidermal blister, prominent eosinophils.
  • Direct Immunofluorescence (DIF): Linear deposition of IgG & C3 along dermoepidermal junction (DEJ).

    ⭐ Direct Immunofluorescence (DIF) showing linear deposition of IgG and/or C3 along the dermoepidermal junction is the gold standard.

  • Indirect Immunofluorescence (IIF): Circulating IgG anti-BMZ antibodies; "roof" pattern on salt-split skin.
  • ELISA: Detects autoantibodies against BPAG1 (BP230) & BPAG2 (BP180, esp. NC16A domain).

Direct immunofluorescence in bullous pemphigoid

Bullous Pemphigoid: Differential Diagnosis - Ruling Out Lookalikes

  • Pemphigus Vulgaris (PV): Flaccid blisters, intraepidermal, +Nikolsky. Oral lesions common.
  • Epidermolysis Bullosa Acquisita (EBA): Subepidermal, trauma-prone sites, scarring. Salt-split skin: IgG on dermal side.
  • Linear IgA Bullous Dermatosis (LABD): Subepidermal, "string of pearls" appearance. Linear IgA at BMZ.
  • Dermatitis Herpetiformis (DH): Grouped pruritic vesicles (extensors). Granular IgA deposits.

⭐ Key differentiator from Pemphigus Vulgaris: BP features subepidermal blisters targeting hemidesmosomes (BPAG1/BP230, BPAG2/BP180). PV shows intraepidermal blisters targeting desmosomes (Desmoglein 1/3).

Bullous Pemphigoid: Treatment Tactics - Quelling the Blisters

  • Primary Goals: Control disease, heal lesions, reduce pruritus, minimize therapy toxicity.
  • Management Approach:

⭐ For generalized bullous pemphigoid, systemic corticosteroids (e.g., prednisolone 0.5-1 mg/kg/day) are the mainstay of treatment, often combined with steroid-sparing agents.

  • Other Options/Adjuvants:
    • Tetracycline (e.g., Doxycycline) + Niacinamide (📌 "TetraNi"): Mild cases or adjuvant.
  • Supportive Care: Wound management, antihistamines for itching.

High‑Yield Points - ⚡ Biggest Takeaways

  • Elderly patients are most commonly affected; it's an autoimmune subepidermal blistering disease.
  • Presents with tense, large bullae on erythematous or urticarial plaques; often preceded by intense pruritus.
  • Nikolsky sign is characteristically negative, distinguishing it from Pemphigus.
  • Direct Immunofluorescence (DIF) shows linear IgG and C3 deposits at the dermoepidermal junction (DEJ).
  • Autoantibodies target hemidesmosomal proteins BPAG1 (BP230) and BPAG2 (BP180/Type XVII collagen).
  • Oral lesions are present in only 10-30% of cases, less common than Pemphigus Vulgaris.

Practice Questions: Bullous Pemphigoid

Test your understanding with these related questions

Which of the following is NOT a characteristic of pemphigus vulgaris?

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Flashcards: Bullous Pemphigoid

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Direct immunofluoresence showing granular deposits at the tips of dermal papillae points to the diagnosis of _____

TAP TO REVEAL ANSWER

Direct immunofluoresence showing granular deposits at the tips of dermal papillae points to the diagnosis of _____

dermatitis herpetiformis

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