involves skin folds, oral mucosa with snail-track erosions and cobblestoning
often due to known or occult inflammatory bowel disease (IBD) so once diagnosed, may respond to empirical IBD Rx such as sulfasalazine, TNF-a inhibitors.
immunobullous conditions:
pemphigus vulgaris
bullous pemphigoid
workup
exclude infection:
wound swabs:
pierce intact pustule and swab for bacteria m/c/s, HSV, VZV viral PCR
skin scrapings for fungal m/c/s and scabies if suspected
general workup:
FBE, UEC, LFT, CRP, ESR
additional workup if suspicious of neutrophilic dermatoses or immunobullous condition:
vasculitis screen
connective tissue screen
skin antibodies for immunobullous DDx
pre-treatment immunosuppressive screen:
Hep B/C, HIV, syphilis, strongyloides serology
Quantiferon Gold
G6PD (if plan to use dapsone)
HLA-B*1301 if suspect risk of hypersensitivity (esp. those of Asian descent)
VZV and MMR antibodies
multiple punch biopsies
histology (sent in formalin) - take from edge of pustule or intact pustule
culture (sent fresh in saline) - take from centre of lesion
direct immunoflourescence (sent fresh in saline) - take from around the lesion in normal skin within 1cm of pustule