The patient is a college-age woman with a history of moderately severe and extensive plaque psoriasis that has been managed with topical corticosteroids. She had been snowboarding over a very cold weekend and developed a pustular rash at night after her activities. She comes to your office on Monday morning and shows you a rash on her hands, which is already fading. This rash is unlike any skin problem she has previously experienced. She recalls no trauma to the hands; however, she remembers removing her gloves to text on her phone while she was sitting on the chair lift.
Examination reveals drying pustules on the acral aspect of her hands. There is no involvement elsewhere.
The differential includes folliculitis; Candida infection; hand, foot, and mouth disease; erythema multiforme; and pustular psoriasis.
This patient has an acute pustular psoriasis that erupted on her hands secondary to cold exposure.
Psoriasis can be seen in a variety of presentations, including guttate, plaque, palmoplantar, inverse, erythrodermic, and pustular variants. Pustular psoriasis is an acute subtype.
Psoriasis is among a group of skin conditions that exhibit the isomorphic, or Koebner, phenomenon. This involves the emergence of psoriasis following trauma on previously healthy skin in an individual with known psoriasis.
In this patient’s case, the acute cold exposure traumatized the skin and resulted in Koebnerization of psoriasis to her hands. The pustular nature of these lesions is linked with their acuity. The acute localized reaction in her case began to resolve within a day of injury without intervention.
A class 1 topical corticosteroid ointment would be a good option for intervention to speed the resolution or to treat more persistent cases. New flare-ups may be avoided by wearing gloves and protecting skin from cold exposure.
Camargo CM, Brotas AM, Ramos-e-Silva M, Carneiro S. Isomorphic phenomenon of Koebner: facts and controversies. Clin Dermatol. 2013;31:741-749.