Psoriasis = Auspitz sign, Munroe microabscess. Lichen planus = 6 Ps, Wickham striae.

Pemphigus = Intraepidermal, flaccid, Nikolsky +. Pemphigoid = Subepidermal, tense.

Primary syphilis = painless chancre. Chancroid = painful ulcer.

Ridley-Jopling: TT→BT→BB→BL→LL. Tuberculoid = paucibacillary, well-defined patches.

KOH mount for diagnosis. Tinea capitis = endothrix/ectothrix. Pityriasis versicolor = spaghetti-meatball.

SJS = <10% BSA. TEN = >30% BSA. Carbamazepine & Allopurinol = common culprits.