Pyogenic Arthritis-Pyoderma Gangrenosum-Acne Syndrome

Pyogenic arthritis-pyoderma gangrenosum-acne syndrome is a rare pleiotropic autoinflammatory disorder of childhood, primarily affecting the joints and skin.

Epidemiology

To date, only 34 patients with PAPA syndrome have been reported worldwide, from five families (two in the USA, one in Italy, one in the Netherlands, and one in New Zealand).

Clinical description

The first affected family contained ten affected members from three generations and manifested variable expression of a pauciarticular, nonaxial, arthritis that began in childhood; pyoderma gangrenosum; and severe cystic acne in adolescence and beyond. PAPA syndrome is a self-limiting disease, but it can lead to severe joint destruction. Synovial fluid is purulent with neutrophil accumulation, but cultures are invariably negative. Recurrent sterile arthritis usually occurs after minor trauma, but can also occur spontaneously. Other less commonly associated features include adult-onset insulin-dependent diabetes mellitus, proteinuria, and abscess formation at the site of parenteral injections (pathergy).

Etiology

The gene responsible for the syndrome, the proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1) gene (previously known as the CD2 binding protein 1 (CD2BP1) gene), was cloned in 2002. Only two mutations account for the known cases. Recently, the PSTPIP1 protein has been demonstrated to bind pyrin/marenostrin (P/M), the protein encoded by the MEFV gene, mutations in which cause Familial Mediterranean Fever. PAPA-associated PSTPIP1 mutants exhibit increased binding to P/M.

Differential diagnosis

Differential diagnosis for PAPA syndrome should include juvenile idiopathic arthritis and periodic fever.

Genetic counseling

PAPA syndrome is inherited in an autosomal dominant manner.

Management and treatment

Arthritis and skin lesions have sometimes been reported to be responsive to glucocorticoids. However, two alternative therapeutics have been suggested so far. In one report, the disease underwent rapid and sustained clinical remission after treatment withthe tumor necrosis factor inhibitor, etanercept. Another recent paper described the effect of recombinant human interleukin (IL)-1 receptor antagonist (anakinra), which appeared to be an effective therapy to treat disease flares in PAPA syndrome.