[The psoriatic great toe or the psoriatic onycho-pachydermo-periostitis of great toe (OP3gt)].

The onycho-pachydermo-periostitis of the great toe is a characteristic feature of psoriatic arthritis first described by Fournié in 1980. In the affected patients, the great toe involvement is characterised by a relevant osteo-periostitis of the distal phalanx, a thickening of the distal soft tissues associated with a psoriatic onychopathy. In most cases, the distal interphalangeal joint is spared. Radiographic and scintigraphic osteo-periostitis of distal phalanx of the great toe are frequent, being found in about 44% of patients with psoriatic arthritis. However, clinical manifestations, with inflammatory inflammation of the great toe, are rare.