Acrodermatitis continua of Hallopeau (syn. acropustulosis)

Acrodermatitis continua of Hallopeau (ACH) is a rare chronic sterile pustular eruption initially affecting the tips of the fingers or toes and slowly extending proximally up the digits, occasionally evolving into generalised pustular psoriasis. ACH is named after the French dermatologist François Henri Hallopeau, who first described the syndrome in 1890. 

This chapter is set out as follows:

• The cause is unknown
• ACH is considered a variant of palmoplantar pustulosis. Patients do not usually have additional plaque psoriasis
• The onset can be triggered by localised trauma or infection

• ACH is most common in adult females
• It may arise in childhood or old age, but rarely in young adults
• Over time, affected digits can become painful, especially in the cold

• The first lesion tends to arise on a finger or thumb more often than on a toe - 80% begin in only one digit, most commonly the thumb
• The skin over the distal phalanx becomes red and scaly, and pustules develop. The pustules often coalesce and on bursting, reveal a painful, red and glazed area where new pustules then develop
• The nail folds and nail bed may be involved, leading to nail dystrophy
• Slow proximal extension is the rule 
• Eventually, other digits may be involved
• Bone changes can occur with osteolysis of the tuft of the distal phalanx resulting in a wasted and tapered tip of the finger or toe, mimicking scleroderma
• Mucosal surface can be affected 
• ACH may evolve into generalised pustular psoriasis, especially in the elderly

• ACH is a long-term condition, occasionally spontaneous remission does occur but is more often temporary than permanent
• Patient's should be referred to Secondary Care
• ACH may be very resistant to treatment
• There is little evidence on which to base treatment options, which include:
  • Potent topical steroids under occlusion 
  • Other topical treatments, eg tacrolimus 0.1% ointment and calcipotriol
  • Acitretin and ciclosporin
  • Some of the biologic therapies