| Disease | Pathophysiology / Target Antigen | Clinical Features & Morphology | Histology / Immunofluorescence (IF) |
|---|---|---|---|
| Pemphigus Vulgaris | IgG against Desmoglein 1 & 3 (Desmosomes) (Type II H.S.) | Flaccid bullae; rupture easily. Oral mucosa involved (often 1st). Nikolsky (+). | Intraepidermal split. ”Row of tombstones” on basalis. IF: Net-like / Reticular IgG pattern. |
| Bullous Pemphigoid | IgG against Hemidesmosomes (BP180/BP230) (Type II H.S.) | Tense bullae; do not rupture easily. Oral mucosa spared. Nikolsky (-). | Subepidermal split. Prominent Eosinophils. IF: Linear IgG at basement membrane. |
| Dermatitis Herpetiformis | IgA against Tissue Transglutaminase (Cross-reacts w/ reticulin) | Pruritic papules/vesicles on extensor surfaces (elbows, knees). Assoc: Celiac Disease. | Microabscesses (neutrophils) at dermal papillae tips. IF: Granular IgA at dermal papillae. |
| Epidermolysis Bullosa | Hereditary defect in anchoring proteins. (e.g., Keratin 5/14 or Collagen VII) | Blisters induced by minor trauma/friction. Presents in infancy/childhood. | Cleavage at Dermal-Epidermal Junction (DEJ). Electron microscopy used for subtypes. |
| Bullous Impetigo | Exfoliative Toxin A (S. aureus) cleaves Desmoglein 1. | Flaccid bullae with honey-colored crust. Rapid spread; contagious. Nikolsky (+). | Subcorneal split (very superficial). Gram stain: Gram (+) cocci in clusters. |
| Condition | Target/Cause | Split Location | Mucosal? | Nikolsky? | Key Buzzword |
|---|---|---|---|---|---|
| SJS/TEN | Drugs | DEJ (Full necrosis) | YES | (+) | Sloughing skin, >30% BSA (TEN) |
| SSSS | S. aureus Toxin | Granulosum (Superficial) | NO | (+) | Newborns, Desmoglein-1 split |
| Pemphigus Vulgaris | Anti-Desmoglein | Suprabasal | YES | (+) | Reticular IF, Tombstone, Flaccid |
| Bullous Pemphigoid | Anti-Hemidesmosome | Subepidermal | No/Rare | (-) | Linear IF, Tense Bullae |
| Dermatitis Herp. | Gluten (IgA) | Dermal Papillae | No | N/A | Pruritic, Extensors, Celiac |