Papillon-Lefèvre syndrome presenting with early-onset Psoriasis and Osteomyelitis: A case report

Papillon-Lefèvre syndrome (PLS) is a rare autosomal recessive disorder caused by mutations in the Cathepsin C (CTSC) gene, characterized by palmoplantar hyperkeratosis, severe periodontitis, and recurrent infections. We present the case of an 8-year-old boy with early-onset psoriasis diagnosed in infancy and managed with Adalimumab. He presented with progressive right knee swelling, and intermittent fever. MRI revealed a Brodie abscess with features of osteomyelitis. Abscess fluid culture was positive for methicillin-resistant Staphylococcus aureus . Whole-exome sequencing identified a homozygous missense variant in the CTSC gene (c.899G>A; p.Gly300Asp), confirming the diagnosis of PLS. Interestingly, his dental panoramic x-ray was normal. This case underscores the importance of genetic testing in patients with early-onset psoriasis and atypical infections. Although almost all reported cases of PLS feature early, severe periodontitis, our patient did not show dental involvement. This highlights that younger patients with PLS may present without this classical feature.