Pemphigus Vulgaris
IgG anti-desmoglein 1/3 (desmosomes); flaccid blisters, positive Nikolsky sign, painful oral mucosal erosions; intraepidermal acantholysis on biopsy.
Bullous Pemphigoid
IgG anti-hemidesmosome (BP180/BP230); tense, firm bullae that do NOT rupture easily, negative Nikolsky sign, spares oral mucosa; subepidermal split.
SJS vs. TEN Cutoffs
SJS: < 10% epidermal detachment; SJS/TEN overlap: 10–30%; TEN: > 30% body surface area detachment with full-thickness epidermal necrosis; SCORTEN prognostic score.
Psoriasis Hallmarks
Well-demarcated salmon-pink plaques with silvery-white scale on extensor surfaces (elbows/knees); Auspitz sign (pinpoint bleeding); Koebner phenomenon.
Autoimmune Blistering Dermatoses Master Comparison
| Disorder | Target Antigen & Level of Blister | Nikolsky Sign & Mucosal Involvement | Direct Immunofluorescence (DIF) Pattern | First-Line Therapy |
|---|---|---|---|---|
| Pemphigus Vulgaris | Desmosomes (anti-desmoglein 1 and 3); Intraepidermal acantholysis with 'tombstoning' of basal keratinocytes | Nikolsky positive (lateral pressure induces new blister/skin sloughing); oral mucosal involvement almost always present | Intercellular IgG and C3 deposition throughout epidermis ('net-like' / 'fishnet' pattern) | Systemic high-dose corticosteroids (Prednisone) + Rituximab (anti-CD20) |
| Bullous Pemphigoid | Hemidesmosomes (BP180 and BP230); Subepidermal blister with eosinophil-rich infiltrate | Nikolsky negative; tense bullae that resist rupture; mucosal involvement rare (< 20%) | Linear IgG and C3 deposition along the epidermal basement membrane zone | High-potency topical corticosteroids (Clobetasol) or oral Prednisone |
| Dermatitis Herpetiformis | Epidermal transglutaminase-3; associated with Celiac disease (HLA-DQ2/DQ8) | Extremely pruritic microvesicles grouped on extensor surfaces (elbows, knees, buttocks) | Granular IgA deposition in dermal papillae | Strict gluten-free diet + oral Dapsone (check G6PD level prior to initiation) |
Severe Cutaneous Adverse Reactions (SCAR): SJS vs. TEN vs. DRESS
| Syndrome | High-Risk Triggering Medications | Pathophysiology & BSA Sloughing | Systemic Involvements & Key Markers |
|---|---|---|---|
| Stevens-Johnson Syndrome (SJS) | Allopurinol, Anticonvulsants (Carbamazepine, Lamotrigine, Phenytoin), Sulfonamides, Nevirapine, NSAIDs | Fas/FasL and perforin/granzyme cytotoxic T-cell death; < 10% BSA detachment; ≥ 2 mucosal surfaces involved | Severe oral/conjunctival erosions, hemorrhagic crusting of lips; Nikolsky positive; SCORTEN mortality score |
| Toxic Epidermal Necrolysis (TEN) | Same triggers as SJS; HLA-B*1502 in Asians taking Carbamazepine | Confluent sheet-like detachment > 30% BSA with full-thickness epidermal necrosis | Emergency transfer to ICU / burn unit; IVIG, Cyclosporine, or Etanercept; strict fluid and thermal balance |
| DRESS Syndrome | Anticonvulsants (Phenytoin, Carbamazepine), Allopurinol, Sulfonamides, Vancomycin; 2–8 weeks latency | Drug Reaction with Eosinophilia and Systemic Symptoms; associated with HHV-6 reactivation | Fever, diffuse morbilliform rash, facial edema, diffuse lymphadenopathy, marked eosinophilia (> 700), acute interstitial nephritis or hepatitis |
OMM Board Correlate: Cutaneous Autonomics & Myofascial Considerations
- Sympathetic Vasomotor Control: Cutaneous blood vessels receive purely sympathetic adrenergic vasoconstrictor innervation (T1–L2). Paraspinal rib raising and soft tissue inhibition normalize autonomic tone to cutaneous microvascular beds.
- Contagion & Barrier Precautions: OMT is directly contraindicated over denuded, infected, or actively blistering cutaneous regions (erythematous plaques, weeping bullae in SJS/TEN or active HSV) to prevent secondary bacteremia and epidermal shearing.
Board Traps & Common Distractors
- In patients presenting with SJS or TEN, IMMEDIATELY discontinue all suspect medications; delays in withdrawing the culprit drug exponentially increase mortality.
- All patients initiating Carbamazepine with Asian ancestry should undergo screening for HLA-B*1502 due to an extraordinarily high risk of fatal Stevens-Johnson Syndrome and TEN.
- Prior to prescribing Dapsone for dermatitis herpetiformis, ALWAYS verify G6PD enzyme levels; Dapsone in G6PD deficiency triggers massive hemolytic anemia and life-threatening methemoglobinemia.