# An Unexpected Dupilumab Reaction

## TL;DR

A rare case of crusted scabies in a patient treated with dupilumab required extended treatment, suggesting a link between the drug and immune suppression.

## Contribution

This is the first reported case requiring a seven-day extended treatment for crusted scabies in a dupilumab-treated patient.

## Key findings

- Crusted scabies in a dupilumab-treated patient required a seven-day extended regimen for resolution.
- Dupilumab may impair the immune system's ability to control scabies mites, leading to persistent infections.
- The case highlights the need for prolonged anti-scabietic treatment in patients receiving dupilumab.

## Abstract

Crusted scabies (CS), a rare and highly contagious variant of scabies, is characterized by the uncontrolled proliferation of Sarcoptes scabiei and can involve thousands of mites per patient. It often mimics hyperkeratotic disorders, complicating its diagnosis, and extended or repeat courses of treatment are often needed for severe cases. Previous reports have described cases of CS occurring after biologic therapy, with some resolving rapidly following ivermectin treatment. In contrast, our case report includes a patient with CS on dupilumab who required a seven-day extended regimen for complete resolution, which has not been previously reported. Dupilumab’s suppression of Th2 responses may impair the immune system's ability to control scabies mites, allowing unchecked proliferation. This case report contributes to the literature by providing new insights and highlights the potential for persistent scabietic infection in patients receiving dupilumab, underscoring the need for prolonged anti-scabietic treatment in such cases. Further research is needed to explore the immune mechanisms behind the development of CS in patients on immunosuppressive therapies.