Stevens Johnson Syndrome and Toxic Epidermal Necrolysis

Closely related. Characteristically severe, diffuse mucocutaneous eruption with atypical flat target lesions, irregular, possibly purpuric, blistering, even haemorrhagic! Painful, like sunburn.  Different pathology from Erythema multiforme! Evolve over 1-2 weeks, subside over further 2-3 weeks.

Other manifestations are fever (prodromal illness can manifest as URTI).  Mucosal lesions (stomatitis, conjunctivitis/blepharitis, or genital inflammation) accompanied by at least 1 other visceral organ, such as hepatic, renal, trach/bronchial or gastrointestinal involvement. Urethral involvement can cause retention of urine. Chest and abdominal signs pretty common!

Urgent ophthalmology – uveitis can lead to blindness.