PAPA syndrome

PAPA syndrome is a rare inherited autoinflammatory disorder whose name stands for pyogenic arthritis, pyoderma gangrenosum and acne, the three features that mark its effects on the joints and skin. It usually begins in early life with destructive arthritis, often set off by an injury, and repeated episodes can damage joints enough to require several replacements. Skin changes become more prominent from puberty: pyoderma gangrenosum appears as poorly healing ulcers with undermined edges and a tendency to arise at sites of injury, while severe nodulocystic acne affects most patients and scars if untreated. The disorder is inherited in an autosomal dominant pattern and traced to mutations in the gene for CD2 binding protein 1, part of an inflammatory pathway shared with other autoinflammatory diseases. Diagnosis can rest on clinical features and family history, with genetic testing as support. Treatment includes antibiotics or isotretinoin for acne, and TNF and interleukin-1 blocking drugs for resistant arthritis and ulcers.