By Gary M. White, MD
Multiple nodules with a central keratotic core on the legs of a dialysis patient.
Acquired perforating disorder (APD), AKA Kyrle disease, is the primary variant of a group of perforating disorders. The underlying process is transepidermal elimination of dermal collagen. Triggers of lesions seem to involve local trauma, e.g., scratching.
APD has been associated with:
Hyperkeratotic papules and nodules develop. A central keratotic plug is characteristic. Lesions may be very pruritic and a component of prurigo nodularis may be present. The lesions are common on the extensor extremities and may spare the back, the so called butterfly sign (lesions only occur where the patient scratches). Lesions may occur in a linear arrangement suggesting the Koebner phenomenon.
Various theories have been proposed with regard to the etiology of APD. Trauma from scratching may induce damage of the epidermis or dermal collagen, leading to transepidermal elimination of collagen or elastic fibers. Alternatively, alteration in collagen or elastic fibers may trigger transelimination. This alteration may be due to metabolic disturbances such as elevated glucose or microdeposition of substances, such as calcium salts related to cases of dialysis. Underlying dermal microvasculopathy related to DM may predispose to APD. Diabetic vasculopathy induces a hypoxic state, in which the trauma from scratching causes dermal necrosis.
No treatment is consistently effective. The patient should be encouraged to not scratch although s/he may not be successful. Topical steroids and emollients to reduce xerosis, itch, and inflammation may be very helpful in some cases [JAMA Derm 2014;150;1371]. UVB may be tried. Both topical and oral retinoids have been used.
Allopurinol has been used effectively in 13 patients (various case reports) with APD. When checked, the uric acid has been within the normal range. The starting dose was 100 mg/day in all patients; in one of them, however, the daily dose had to be increased up to 300 mg and in another was reduced to 50mg/day. Improvement was noticed within 1-4 weeks in 8 patients and within 24 months in 5 patients [An Bras Dermatol. 2013; 88:94].
Diabetes x 18 years. Virtual Grand Rounds in Dermatology
Dermatol Pract Concept. 2015 Apr; 5(2): 75–77
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