Pemphigus

Basics

Description

  • Autoantibody (IgG)-mediated blistering disease of the epidermis and mucous membranes:
    • Characterized by loss of cell-to-cell adhesion called acantholysis
  • Age of onset 45–65 yr in most populations:
    • Reports of disease occurring in neonates through elderly
  • Rare; worldwide incidence 0.7/100,000
  • Women more often than men (66%)
  • Pemphix is Greek for bubble or blister
  • Pemphigus – specific term for autoantibody disease-targeting desmogleins (Dsgs) which are cell-to-cell adhesion molecules
  • Mortality is highest in those with mucocutaneous involvement:
    • If untreated, mortality rates average 60–90%; with treatment this nears 5%
  • 3 major subtypes exist:
    • Pemphigus vulgaris; typically more serious with deeper mucocutaneous involvement:
      • Accounts for 70–80% of all pemphigus
      • Up to 70% present with oral lesions
      • May or may not have skin involvement
      • Flaccid bullae
      • Autoantibodies to Dsg 1 and 3
      • Affects most races in middle age
    • Pemphigus foliaceus; milder and more superficial cutaneous lesions:
      • Involves skin only
      • Autoantibodies to Dsg 1 only
    • Paraneoplastic pemphigus; often with severe mucocutaneous involvement:
      • Most commonly seen in lymphoreticular malignancies
      • Contrasted with pemphigoid: A term describing the group of syndromes that cause a separation of the epidermis from the dermis, typically more benign course:
      • Bullous pemphigoid has tense bullae that arise from the subepidermal layer and are not as fragile as pemphigus:
        • Negative Nikolsky sign
        • Age of onset 60–80 yr
        • Often has pruritus prior to blistering (prodrome may be present for months)
        • Oral lesions are rare
        • Predominantly affects flexor aspects
        • IgG autoantibodies to hemidesmosomes
        • Direct immunofluorescence shows linear deposition of IgG and C3 at the basement membrane

Pediatric Considerations

  • Pemphigus is rare in neonates and children but may occur in adolescents
  • Early diagnosis and treatment significantly impact growth, psychological, social, and cultural development
  • Histopathology is identical to adult disease
  • Neonates may develop the disease secondary to transplacental transfer of IgG
  • Neonatal pemphigus spontaneously resolves in several weeks as the maternal antibodies are catabolized

Pregnancy Considerations

  • Effective treatment of maternal disease prior to conception lowers the risk of neonatal transmission and gestational complications
  • Pregnancy may precipitate or aggravate pemphigus

Etiology

  • IgG autoantibodies are directed against desmosomal cadherins Dsg 1 and Dsg 3 found in a keratinocytes
  • Autoantibodies cause histopathologic acantholysis, cytoskeletal derangements, and apoptosis
  • Bullae formation is caused by the loss of cell–cell adhesion and separation of the keratinocytes
  • Immunogenetic predisposition secondary to higher frequencies of specific human leukocyte antigen HLA haplotypes including DR4 and DRw6
  • Individuals of Jewish (especially Ashkenazi), Indian, Southeast European Middle Eastern descent are more susceptible to pemphigus vulgaris
  • Drugs such as penicillamine, captopril, rifampin, piroxicam, and phenobarbital can trigger pemphigoid reactions
  • Endemic pemphigus foliaceus most common in South America, may be triggered or transmitted by bites from flying insects:
    • Known in Brazil as fogo selvagem (wild fire)
  • Pemphigoid reactions may occur in association with a neoplasm, usually lymphoma (paraneoplastic pemphigus):
    • Polymorphous clinical presentation with features similar to pemphigus vulgaris as well as bullous pemphigoid

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