Do you ever have a patient with a rash you just don’t recognize?  If you’re like me, it happens all the time and it can be hard to organize your differential.  Michelle Lin (https://aliemcards.com/cards/rash-unknown) published a great set of differentials for the dangerous rashes that I think might make this less garbled and difficult.

AGE <5: Meningococcemia, Kawasaki, Viral Exanthema

Diffuse Erythema: Staph Scaled Skin, Toxic Shock Syndrome, Necrotizing Fasciitis

Mucosal Lesions: Erythemia Ultiforme Major, TEN/SJS, Pemphigus Vulgaris

Assoc. with Hypotension:  Meningococcemia, Toxic shock Synd, Rocky Mountain Spotted Fever, TEN/SJS

Maculopapular rash workup pathway

Petechial or purpuric rash workup pathway

Vesiculobullous rash workup pathway