# Severe atypical juvenile pityriasis rubra pilaris diagnosed in adulthood with a dramatic improvement with ustekinumab

## TL;DR

A rare skin condition diagnosed in adulthood showed significant improvement with a specific drug and genetic testing helped confirm the diagnosis.

## Contribution

This case report highlights the successful treatment of atypical juvenile PRP with ustekinumab and the importance of genetic testing.

## Key findings

- Atypical juvenile PRP was definitively diagnosed in adulthood through genetic testing.
- The patient showed dramatic improvement with ustekinumab treatment.
- The presence of a CARD14 mutation was identified in the patient.

## Abstract

Pityriasis rubra pilaris (PRP) is a rare skin disease which manifests as a psoriasiform dermatosis and palmoplantar keratoderma and has significant clinical‐histopathological overlap with psoriasis. Recently, several case reports have demonstrated successful treatment of PRP with anti‐IL7A and anti‐IL12/anti‐IL23 monoclonal antibodies. We report a case of atypical juvenile PRP definitively diagnosed during adulthood with presence of CARD14 mutation. This case demonstrates a dramatic improvement with ustekinumab and highlights the role of genetic testing in chronic disease of diagnostic uncertainty.

Pityriasis rubra pilaris (PRP) is a rare skin disease which manifests as a psoriasiform dermatosis and palmoplantar keratoderma and has significant clinical‐histopathological overlap with psoriasis. We report a case of atypical juvenile PRP definitively diagnosed during adulthood with presence of CARD14 mutation. This case demonstrates a dramatic improvement with ustekinumab and highlights the role of genetic testing in chronic disease of diagnostic uncertainty.