Acrodermatitis continua of Hallopeau (ACH, also known as acrodermatitis perstans and dermatitis repens) is a rare subtype of pustular psoriasis. It typically presents as recurrent, painful pustules that involve one or more distal digit. Pustules are superseded by scaly psoriasiform plaques in involved areas. These in turn develop new pustules. The lesions may spread proximally to affect larger areas of the hands, feet, and forearms. ACH may involve the nail bed and distal phalanx, resulting in onycholysis, anonychia, and osteolysis of the distal phalanx.

ACH most commonly affects women over the age of 35 but can rarely affect children. The exact etiology is unknown. Mutations in the IL36RN gene have been associated with the development of ACH and pustular psoriasis.

ACH often has a chronic, relapsing course. There are rare reports of ACH developing from and progressing to generalized pustular psoriasis. Nonetheless, psoriatic arthritis is not commonly seen with ACH.