This patient had prurigo nodularis (PN). The diagnosis usually is made clinically by the appearance of the lesions and the cycle of severe pruritus and scratching. In this case, the patient had acutely excoriated lesions in addition to more chronic lesions that had become hyperpigmented nodules. The distribution pattern on his back was typical and highlighted the clinical course of PN. There were no lesions present where the patient was unable to scratch; however, lesions were present where he could reach, hence the term Picker’s nodules. Often, these patients have a history of atopic dermatitis, and anxiety may play a role in patients nervously scratching the lesions.
Biopsy is indicated if there is suspicion of bullous pemphigoid or cutaneous T-cell lymphoma. Pathology of PN shows increased density of nerve fibers in the dermis along with an increased number of T cells, mast cells, and eosinophilic granulocytes. Most patients do not require biopsy unless the diagnosis is in doubt.
Treatment can be difficult due to the severe pruritis and subsequent scratching that appears to prolong the chronic cycle of inflammation. Daily use of nonsedating antihistamines (eg, loratadine, cetirizine) may help reduce pruritus and break the cycle. Sedating antihistamines (eg, diphenhydramine, hydroxyzine) can be used cautiously at bedtime; cotton gloves worn while sleeping may reduce nocturnal scratching and excoriations.
Topical steroids (eg, triamcinolone, betamethasone) can reduce the itching and local inflammation. Emollients can help with associated dyshidrosis and eczema, if present.
Second line therapies include topical calcineurin inhibitors (eg, tacrolimus, pimecrolimus), calcipotriene, and narrow beam UVB therapy.
This patient had done reasonably well with cetirizine and triamcinolone in the past, so treatment was restarted. He was counseled regarding the nature and chronicity of his PN and told that if he could achieve symptom control and stop scratching the lesions, his condition might resolve.
Photo and text courtesy of Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque.