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Intraepidermal Blisters

ballooning degeneration HSV/VZV

acantholysis mainly pemphigus vulgaris

spongiosis

adults: eczema herpeticatum (disseminated HSV) [dermis]

moderate: 1^st generation cephalosporin

rarer form: impetigo herpetiformis [dermis]

tinea (see micro)

scalded skin (see micro)

cellulitis (see other)

Subepidermal Blisters

pruritic / more common than erythema multiforme / consider outpatient skin testing /

systemic steroids hardly ever used for this now
Type II (cytotoxic, cytolytic) (see immuno)
Pemphigus (Pemphigus vulgaris) – serious, rare [dermis]

Pathology: IgG or IgM, complement in epidermis intercellularly / eosinophils

Presentation: can be difficult to diagnose with oral lesions preceding cutaneous lesions by weeks/months

pemphigus vulgaris (oral lesions / intact blisters are common) [pic]

pemphigus foliaceus (superficial, oral lesions / intact blisters are rare)

Findings: skin sloughs away (Nikolsky’s sign) / intraepidermal blisters should be able to be advanced with application of external pressure (there’s probably a name for this)

Complications: loss of electrolytes, super-infections, associated with malignancies (e.g. lymphoma)

Ddx: paraneoplastic pemphigus

Treatment: high-dose systemic steroids (120-150 qd then prednisone 60-80 mg and steroid-sparing agent (e.g. Immuran 50 mg bid or plasma exchange, Cytoxan, Cellcept) then prednisone 50 mg qod (gradual steroid taper may take up to a year)

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  rituximab (newly used; alone and in combination)
  

painful mucosal ulcerations [pic][pic], polymorphic skin lesions (scalded skin [pic], conjunctivitis [pic], EM [pic]

lymphoreticular malignancies

Pathology: vacuolization of basal cells, keratinocyte necrosis, acantholysis / pemphigus/pemphigoid-like Ig / special IF on rat bladder shows intracellular Ab’s / HLA-Cw14 and HLA-DRB103

Treatment: treat underlying malignancy / prednisone or cyclosporin or plasmapheresis
Senear-Usher syndrome [dermis]

overlap syndrome with features of lupus erythematosus (LE) and pemphigus foliaceus

Mainly in elderly

Presentation: urticaria-like and pruritic, erythematous lesions gradually give way to tense, sub-epidermal bullae on erythematous or normal-appearing skin / groin, axilla, and flexural areas / no acantholysis, minimal or no mucosal lesions / lesions may come and go without treatment / can verify blisters are subepidermal by pressing on the intact blister edge (if it extends it’s likely some other blistering process)

Pathology: linear band of IgG, C3 at basement membrane / eosinophils

similar to pemphigoid / 2nd trimester

group of diseases (mostly congenital) / lesions mostly in area of friction and trauma / no immunofluorescence / come and go indefinitely / variable severity, can be fatal / often results in severe anemia (give Epogen and IV iron)

uncommon, HLA B8, DR3 / associated with celiac disease (20% with lab-evidence of malabsorption, 4% symptomatic celiac-sprue)

Pathology: vesicles are subepidermal, with neutrophilic infiltrate in upper dermis / direct IF shows IgA along the basement membrane in dermal papillae / some say IgG also present (activates alternative complement)

Lesions non-pruritic / can be drug-induced

pathogenesis is similar to GVHD of skin / lymphocytes may have non-specific immune complex, complement deposition / common reaction to infection, drugs (usu. started 1-3 wks before onset)

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  common: phenytoin, barbiturates, sulfonamides, penicillins, NSAIDs