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.
Toxic epidermal necrolysis = body surface area detachment >30%. SJS typically less than 10% detachment. Monitor using body maps.
Some genetic risk factors – eg S Asians.
Drug induced may not appear until up to 28/7 from start of treatment. Penicillin, other antibiotics, NSAIDs, anti epileptics are the usual causes. Consider any medicine (including oral contraceptive) in previous 2 months!? HSV, Coxsackie, influenza, EBV, Adenovirus, Enterovirus, strep A, mycoplasma, chlamydia.
Subepidermal bullae seen on biopsy (if done – no need usually). Do 2, just adjacent to blister. Direct immunofluorescence to exclude an immunobullous disorder. If staphylococcal scalded skin syndrome suspected, shave biopsy of blister roof for frozen section sufficient.
Beware BP cuffs, adhesive ECG leads and dressings. Wrist tags can cause trauma. Use soft silicone tapes, tubular bandages, adhesive remover. Chlorhexidine or even betnesol Mouthwash, topical anaesthetics. Burns unit? Decompress blisters but leave dead skin in place. 50:50 WSP and/or emollient sprays. Irrigation, non adherent dressings. Wet dressings for genitals. Avoid giving NSAIDs, codeine, given that they are associated with SJS!
Consider betnovate for erythematous, non detached areas once infection excluded.
Complications include Hyper/hypopigmentation, Onycholysis, depapillation of tongue. Adhesions, entropion, trichiasis. Not scarring unless secondary infection. GI strictures, blindness (as complication of uveitis) can occur.
Usually treated with steroids but controversial since some retrospective studies showed harm. IVIg given in addition has been disappointing, although has been associated with nephrotoxicity in adults. Seems to be T-cell mediated: CD8, CD56.