Pemphigus vulgaris (PV) is an autoimmune disease of the skin and mucous membranes characterized by suprabasal acantholysis and formation of blisters and erosions due to generation of IgG autoantibodies directed against desmosomal proteins. Tissue expanders are devices that, through controlled mechanical overstretch, are capable of generating new skin that is used to cover wounds or extended surgical defects. We report the case of a 13-year-old girl suffering from Crohn's disease (CD) and primary sclerosing cholangitis (PSC) who developed PV after application of a tissue expander for surgical removal of a giant congenital melanocytic nevus (GCMN). To the best of our knowledge, the case presented here is the first report of PV possibly associated with the application of a tissue expander and also the first report of coexistence of PV with either PSC or with PSC and CD in the same patient. Triggering or acute exacerbation of PV may be considered a possible side-effect of tissue expander application, especially in patients with a genetic predisposition for pemphigus and/or other autoimmune diseases. In view of the increasing use of tissue expanders in clinical practice, physicians should be aware of this rare side-effect in order to promptly diagnose it.