Allopurinol in the treatment of acquired reactive perforating collagenosis
A 73-year-old man was admitted with intensively pruritic multiple erythematous excoriated papules and nodules with a central adherent keratotic plug up to 20mm in diameter involving the whole integument. Pruritus had started 10 months before and subsequently there was onset of keratotic papules and nodules (). The patient had suffered from diabetes type 1 for 50 years, complicated with retinopathy, cardiopathy, chronic renal failure and, in the last 5 years, also with secondary hyperparathyroidism. Medication consisted of insulin, bisoprolol, clopidogrel, telmisartan, nicorandil, furosemide, calcium dobesilate and ranitidine. Laboratory tests showed elevated creatinine 1.72mg/dl (0.7-1.20), urea 106mg/dl (10-45), potassium 5.5 mmol/l (3.5-5.0), HbA1c 8.0% (4.3-5.9), parathormon 89.8pg/ml (15.0-65.0), lymphocytes with 12% (20-40.0); uric acid 6.1mg/dl (3.4-7.0) was within normal range.\nHistopathology showed irregular epidermal hyperplasia with hypergranulosis, orthokeratosis and a cup-shaped depression of the epidermis with parakeratotic material, debris and extruded basophilic collagen fibres at the bottom (). Fibrosis and a perivascular lymphoplasmacellular infiltrate were present in the dermis.\nThe diagnosis of ARPC was made. The patient was initially given a 2-week course of antihistamines p.o.. Topically applied corticosteroids and 6-week narrow-band ultraviolet-B phototherapy were also tried. As pruritus and skin lesions persisted, allopurinol 100mg once/day p.o. was started. Skin lesions and pruritus improved within 4 weeks, in fact the lesions resolved to postinflammatory hyperpigmentations. Clinical response was maintained at 14-month follow-up visit with uninterrupted well-tolerated allopurinol therapy ().