The Hidden Cause of Maculopapular Rash in Interleukin-12 Deficiency.

Interleukin-12 RB1 (IL12RB1) deficiency falls under the Mendelian susceptibility to mycobacterial disease. It is a rare genetic disease with autosomal recessive inheritance. It is characterized by recurrent infections with otherwise weak bacteria, such as mycobacteria and . Often, when encountering a maculopapular eruption, a drug-related cause comes to mind. However, we report a case of IL12RB1 deficiency presenting with a maculopapular eruption, proven by a skin biopsy to be leukocytoclastic vasculitis. The patient was given antibiotics, which improved her skin lesions. Vasculitis should be considered in the differential diagnosis in patients with IL12RB1 deficiency presenting with a cutaneous eruption.