Acute generalized exanthematous pustulosis simulating Stevens-Johnson syndrome/toxic epidermal necrolysis associated with the use of vismodegib

AGEP: acute generalized exanthematous pustulosis BCC: basal cell carcinoma SJS/TEN: Stevens-Johnson syndrome/toxic epidermal necrolysis INTRODUCTION Basal cell carcinoma (BCC) is a common skin neoplasm that usually has a nonaggressive behavior typically managed with local treatment (eg, surgery, photodynamic treatment, topical agents, or radiation). In some cases, BCC has a much more invasive behavior (locally advanced or metastatic BCC), which may require systemic treatment. An abnormal activation of the hedgehog pathway signaling has been linked to the pathogenesis of BCC. Vismodegib is the first-in-class inhibitor of this pathway. Patients with inoperable or unresectable disease are candidates for this treatment. Primary concerns while treating with vismodegib are its multiple adverse effects: muscle spasms, diffuse alopecia, dysgeusia, weight loss, asthenia, and anorexia. Most patients suffer at least 1 adverse effect. Most adverse effects appear early in the course of treatment, are mild or moderate (grade 1-2), and are thought to be related to the inhibition of hedgehog signal transduction. The most common serious adverse effects reported are pneumonia, worsening of general physical health, squamous cell carcinoma, and dehydration. In the largest clinical trial, vismodegib-induced cutaneous adverse effects were described as alopecia, folliculitis, maculopapular rash, or dermatitis. In this study, 2 patients (0.4%) presented a grade 3 maculopapular rash; nevertheless, no further information about these cases is provided by the investigators. Moreover, there are no reports of severe mucocutaneous reactions to vismodegib in the literature.