3.2 - Autoimmune Blistering Disease

Pemphigus vulgaris and mucous membrane pemphigoid are type II autoimmune diseases, but the target decides everything.

pemphigus vulgaris vs mucous membrane pemphigoid

target decides everything

• pemphigus vulgaris — targets desmosomes

  • desmoglein 1 and 3, which hold epithelial cells together

  • cells come apart from one antoher

  • split within epithelium, just above basal layer

• mucous membrane pemphigoid — targets basement membrane

  • BP180 and laminin 332, which anchor epithelium to connective tissue

  • whole epithelium lifts off

  • split beneath the epithelium

pemphigus vulgaris

type II autoimmune hypersensitivity that targets desmosomes, splitting within epithelium above basal layer

• IgG autoantibodies agaisnt desmoglein 3 (mucosa) and desmoglein 1 (skin)

  • destroys desmosomal adhesion, causing epithelial cells to separate from each other

• uncommon, usually seen in individuals in 40s to 60s

  • more common in people of Ashkenazi Jewish and Mediterranean descent

• histology findings —

  • acantholysis → keratinocytes lose attachment and become round

  • Tzanck cells → detached rounded cells

  • suprabasal split → basal cells stay attached, like a row of tombstones

• clinical findings —

  • oral lesions are the first sign, sometimes months before skin

  • blisters are rarely seen intact → thin roof ruptures, leaving ragged and painful erosions

    • at any site including buccal mucosa, gingiva, lips, palate

  • positive Nikolsky sign → gentle friction separates epithelium

• treatment — systemic corticoids and rituximab managed by dermatology

  • potentially fatal if left untreated

• immunofluorescence — intracellular IgG, a net pattern

mucous membrane pemphigoid

type II autoimmune hypersensitivity that targets basement membrane, splitting beneath epithelium

• BP180 and laminin 332 connect epithelium to basement membrane

• clinical findings —

  • subepithelial split → thicker roof so vesicles, sometimes blood-filled, may stay intact briefly

  • gingiva is most common site → desquamative gingivitis

    • red, eroded peeling gingiva

• heals with scarring, but eye is the danger

  • conjunctiva involved in substantial portion of patients

    • scarring → symblepharon (eyelid fused to eyeball), entropion, inturned eyelashes

    • can progress to blindness

  • refer to ophthalmology, even without eye symptoms

  • also ask about nose, throat, esophagus, and genitals

    • laryngeal or esophageal scarring can threaten breathing and swallowing

• immunofluorescence — linear deposits along basement membrane

taking biopsy

two specimens in two medias

• routine histology — lesional tissue in formalin

• direct immunofluorescence — perilesional tissue, intact mucosa next to lesion, in Michel’s medium

  • formalin destroys immunofluorescence specimen

• avoid center or erosion → epithelium already gone

• serum tests can detect circulating antibodies to desmoglein or BP180

desquamative gingivitis

red, eroded, peeling gingiva that does not respond to plaque control

• most often erosive lichen planus or mucous membrane pemphigoid, less often pemphigus vulgaris

• do not keep treating it as plaque-induced gingivitis

  • biopsy with immunofluorescence

• confirmed pemphigoid limited to the gingiva

  • topical corticosteroids, often in a custom tray

  • gentle, meticulous oral hygiene