Paraneoplastic pemphigus mimicking toxic epidermal necrolysis: An underdiagnosed entity?

CLL: chronic lymphocytic leukemia DSG: desmoglein ELISA: enzyme-linked immunosorbent assay EP: envoplakin PNP: paraneoplastic pemphigus IIF: indirect immunofluorescence PP: periplakin SJS: Stevens-Johnson syndrome TEN: toxic epidermal necrolysis INTRODUCTION Paraneoplastic pemphigus (PNP) is an autoimmune blistering syndrome with 5 well-described clinicopathologic phenotypes. Nguyen et al categorized these subtypes as pemphigus-like, pemphigoid-like, erythema multiforme-like, graftvs-host-diseaseelike, and lichen planuselike. However, there is increasing recognition of PNP simulating Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Herein, we propose SJS/TEN-like PNP as a distinct subtype of PNP. We present 2 new cases of SJS/TEN-like PNP and review the previously reported cases of this subtype. Clinicopathologic factors that merit consideration for PNP in this context include a history of associated underlying neoplasia, the absence of a new drug, and histopathology indicative of chronicity or acantholysis. In patients with these features and clinical morphology typical of SJS/TEN, serologic evaluation for IgG autoantibodies against envoplakin (EP), desmoglein (DSG) 1, and DSG3 should be considered in order to exclude SJS/TEN-like PNP.