Approach to Vesiculo-bullous Disorders

When assessing vesiculo-bullous diseases first assess the anatomic level of split. Then an assessment of the mechanisms of split may be helpful; whether the process appears spongiotic, acantholytic or if there is ballooning degeneration of keratinocytes. For subepidermal blisters then assess the inflammatory cell infiltrate. Asssess whether there are eosinophils, neutrophils, lymphocytes or little inflammation. Assess morphological features to identify any features that might point to a specific diagnosis. Finally Direct immunoflorescence.

Intra-epidermal /Subcorneal 

  • Impetigo – Subcorneal neutrophils
  • Fungi
  • Staph “scalding skin” syndrome  – Difficult to get an intact blister as the stratum corneum is often cast off.

Intra-epidermal

  • Friction
  • Viruses (Herpes, Varicella Zoster)

Suprabasal

  • Pemphigus vulgaris –  Suprabasal bullae with acantholyis. “Tombstone” appearance of basal cells adherent to the dermis. Few mixed eosinophils and polys. DIF: linear IgG  mesh at the intracellular junction. Antibodies against desmoglein 3 – intracellular junction protein
  • Hailey Hailey –Acantholytic. Familial.  Dilapidated brick wall appearance
  • Dariers – Dyskeratotic acanthosis. Familial. Dyskeratotic cells, corps ronds & grains.
  • Glovers – Transient acanthosis. Non familial. May have any of the above patterns of pemphigus, HH & Dariers. Clinical.

Subepidermal

Eosinophils

  • Bullous pemphigoid – linear IgG, C3, IgA along the basement membrane (in early/prodromal lesions there may be only dermal oedema with a few eosinophils and only linear C3)

Neutrophils

  • Dermatitis herpetiformis – IgA antibodies against skin transglutaminases. 90% have Coeliacs. Microabscesses in tips of dermal papillae. DIF: Granular IgA at dermal papillae.
  • Linear IgA disease – Histologically identical to DH however no gluten sensitive enteropathy or IgA antiendomysial antibodies.
  • Bullous lupus erythematosis – Vesiculobullous SLE, similar to DH with subepidermal blister and papillary microabscesses. DIF: IgG, C3, IgA

Lymphocytic

  • Erythema multiforme –
  • Others: Lichen sclerosis, Lichen planus pemphigoides, Polymorphic light eruption, Dermal allergic contact dermatitis, Bullous mycosis fungoides

No inflammation

  • Epidermolysis bullosa -(simplex, acquisita) group of conditions with blisters and erosions following minor trauma to the skin
  • Porphyria cutanea tarda – Subepidermal blister with minimal inflam and preservation of the dermal papillae of the floor (festooning). Pas positive Diastase resistant hyaline material in the walls of the small vessels of the dermis and sometimes BM of epidermis.
  • Toxic epidermal necrosis – Severe end of erythema multiforme. Necrosis of the epidermis.
  • Burns

Reference:

Wheedon’s. Skin Pathology. 3rd Ed.

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