Pustular Psoriasis

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Overview & Classification - Pustule Parade

  • Characterized by widespread or localized sterile pustules on erythematous base; distinct from plaque psoriasis.
  • Can be life-threatening (e.g., GPP).

Classification:

  • Generalized Pustular Psoriasis (GPP)
    • Von Zumbusch variant (acute, febrile)
    • Impetigo herpetiformis (psoriasis of pregnancy)
    • Annular/circinate variant
    • Infantile/juvenile GPP
  • Localized Pustular Psoriasis
    • Palmoplantar Pustulosis (PPP)
    • Acrodermatitis Continua of Hallopeau (ACH)

⭐ Generalized Pustular Psoriasis (GPP) can be triggered by rapid withdrawal of systemic corticosteroids or potent topical steroids, infections, or certain medications (e.g., lithium, antimalarials).

Generalized Pustular Psoriasis (GPP) - Fiery Outbreak

  • Acute, severe, potentially life-threatening; widespread sterile pustules coalescing into "lakes of pus" on erythematous skin.
  • Systemic: high fever, chills, arthralgia, ↑leukocytosis.
  • Triggers:
    • Corticosteroid withdrawal (most common).
    • Infections, hypocalcemia, pregnancy (impetigo herpetiformis), drugs (lithium, antimalarials).
  • Skin: fiery red, tender, burning. Nail changes common.
  • Management: Hospitalization. First-line: Acitretin. Alternatives: Cyclosporine, Methotrexate, Biologics (e.g., infliximab). Avoid systemic steroids (rebound risk). Generalized pustular psoriasis with lakes of pus

⭐ Impetigo herpetiformis is GPP of pregnancy, often linked to hypocalcemia and typically occurs in the third trimester.

Localized Pustular Psoriasis - Sticky Spots

  • Chronic, relapsing sterile pustules on specific sites.
  • Palmoplantar Pustulosis (PPP):
    • Palms & soles; often symmetrical.
    • Yellow pustules, erythema, scaling, fissures.
    • Strongly associated with smoking (up to 95%).
    • Nail involvement common.
  • Acrodermatitis Continua of Hallopeau (ACH):
    • Rare; affects distal digits (fingers/toes), periungual.
    • Painful pustules, nail dystrophy, onycholysis, anonychia.
    • May lead to osteolysis. Sterile pustules on palm in Palmoplantar Pustulosis

⭐ ACH can cause irreversible bone resorption (osteolysis) of the distal phalanx an_d nail loss (anonychia).

Pathogenesis & Histology - Microscopic Mayhem

  • Pathogenesis:
    • Genetic: IL36RN mutations (DITRA - Deficiency of IL-36 Receptor Antagonist).
    • Triggers: Infections, stress, rapid steroid withdrawal, hypocalcemia, pregnancy.
    • Key Cytokines: ↑ IL-36, IL-1, IL-17, IL-23, TNF-α → massive neutrophil chemotaxis.
  • Histology:
    • Kogoj's spongiform pustules: Hallmark; intraepidermal neutrophil collections.
    • Munro's microabscesses: Neutrophils in stratum corneum.
    • Epidermis: Acanthosis, parakeratosis.
    • Dermis: Papillary edema, perivascular infiltrate (neutrophils, lymphocytes).

Kogoj's Spongiform Pustule in Pustular Psoriasis

IL36RN gene mutations are strongly linked to Generalized Pustular Psoriasis (GPP), resulting in DITRA syndrome and uncontrolled IL-36 inflammation.

Diagnosis & Management - Calming the Storm

  • Diagnosis:
    • Clinical: Sudden widespread sterile pustules, erythema, fever, pain.
    • Biopsy: Kogoj's spongiform pustules (key).
    • Labs: Leukocytosis (neutrophilia), ↑ESR/CRP, hypocalcemia.
  • Management:
    • Goals: Rapid pustule clearance, systemic symptom control.
    • Supportive: Hydration, electrolyte correction (esp. Ca), emollients.
    • GPP (Generalized Pustular Psoriasis): Hospitalize.
      • Systemic 1st line: Acitretin (0.5-1 mg/kg/d), Cyclosporine (2.5-5 mg/kg/d), Biologics (e.g., Infliximab, Spesolimab).
      • Alternatives: Methotrexate (slower), other biologics (IL-17, IL-23 inhibitors).
    • Localized (e.g., Palmoplantar Pustulosis - PPP): Potent topical steroids + Vit D analogs. Refractory: Acitretin.
    • ⚠️ Avoid abrupt systemic steroid withdrawal (risk of severe rebound).

⭐ Spesolimab, an IL-36 receptor antibody, is a targeted therapy for GPP flares.

High‑Yield Points - ⚡ Biggest Takeaways

  • Generalized Pustular Psoriasis (GPP/von Zumbusch) is an acute, febrile, life-threatening systemic illness.
  • Pustules in GPP are widespread, sterile, and develop rapidly on an erythematous base.
  • Key GPP triggers: systemic steroid withdrawal, infections, hypocalcemia, pregnancy (impetigo herpetiformis).
  • Palmoplantar Pustulosis (PPP) presents with chronic, sterile pustules on palms and soles; strong smoking association.
  • Acrodermatitis Continua of Hallopeau (ACH) affects distal digits and nails, potentially leading to onychodystrophy and osteolysis.
  • Histopathology classically shows Kogoj's spongiform pustules (subcorneal/intraepidermal neutrophilic aggregates).
  • GPP management often requires systemic therapy: acitretin (first-line), cyclosporine, methotrexate, or biologics (e.g., IL-36R inhibitors).

Practice Questions: Pustular Psoriasis

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All are nail changes seen in cases of psoriasis except:

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Flashcards: Pustular Psoriasis

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The scalp, elbows knees, lower back, and gluteal cleft are the commonest areas to be affected by _____ psoriasis.

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The scalp, elbows knees, lower back, and gluteal cleft are the commonest areas to be affected by _____ psoriasis.

plaque

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