SJS

So the clinical picture may be difficult to decipher without a history or full skin exam, but let’s use some of the answers we got to discuss the skin findings above.

One of the answers submitted said it Kaposi Sarcoma, see to the left. The classic presentation of Kaposi’s is multiple violaceous papules and plaques. Make note of the COLORING of the lesions. In contrast, the trivia rash is made up of atypical target lesions. Take a close look at the rash and you will see that there is a dark center with a lighter erythematous border, 2 areas of color. Typical target lesions have THREE areas, often seen in Erythema Multiforme and Lyme Disease.

On the right was another submission - Purpura Fulminans. Again this rash is made up of retiform purpura with branched or angular purpuric lesions. Made note of the SHAPE of the lesions, the picture on the right shows purpura fulminans. Again, our rash had atypical target lesions with the start of some bullae formation.

The trivia rash is of early SJS, which can be characterized by atypical target lesions. Make sure to check their oral mucosa and take a good medication history.

As I was preparing for AHD: Derm, I was curious about the pathophysiology of DRESS and SJS - they are both drug reactions, so why are they so different? Looking into the pathophysiology, they are both the result of a medication activating t-cells via MHC pathway. In SJS, this leads to Killer T-Cells attacking Keratinocytes - causing a rash within days of exposure and causing desquamation. SJS is not typically associated with significant systemic issues. DRESS, however, is thought to be a result of viral reactivation after t-cell activation. This could be why the DRESS is often more delayed to weeks after exposure, the rash is morbiliform, it resembles viral exanthems, and is associated with -itis’s of different organs.