PS12: Successful treatment of compulsive skin-picking disorder with oral N-acetylcysteine

Emily Pender, Liana Victory, Orla McFeely and Ian McDonald

Mater Misericordiae University Hospital, Dublin, Ireland

A 38-year-old woman was referred to the dermatology clinic with a 20-year history of recurrent skin lesions, described on referral as ‘scarring papular eruptions’. Medical history included depression and anxiety, fibromyalgia and congenital cardiac defect. She had previously been treated for acne, with oral isotretinoin and antibiotics, and for nodular prurigo with phototherapy. She reported improvement with oral antibiotics, topical antibiotic/steroid combination and occlusion but that her skin flared upon cessation. She had undergone skin biopsy 18 years prior, showing healing ulceration only. Examination revealed excoriated lesions affecting the face, chest and upper arms, with extensive hypopigmented scarring affecting the face, chest, upper back, arms and thighs. Score on the pruritus numerical rating scale was 3/10 on day of review, but up to 10/10 in the preceding days. Dermatology Life Quality Index was 16/30. There was no evidence of primary dermatosis. The clinical impression was that of excoriation with compulsive skin-picking disorder. Topical fusidic acid/betamethasone was prescribed to affected areas, alongside emollient with menthol and antihistamine. On return to the outpatient department, her skin had improved but lesions had not resolved. Oral N-acetylcysteine (NAC) was initiated at 600 mg twice daily. Three months after commencing NAC, she attended for review. For the first time, her face was clear of excoriations and the lesions on the trunk and limbs had reduced in number. Skin-picking disorder is a debilitating skin condition and has an estimated prevalence of up to 5% (Grant JE, Chamberlain SR, Redden SA et al. N-acetylcysteine in the treatment of excoriation disorder. JAMA Psychiatry 2016; 73: 490). Glutamate appears to mediate reward-seeking behaviour, and glutamate dysfunction is implicated in compulsive disorders, including skin-picking disorder. NAC increases extracellular levels of glutamate within the nucleus accumbens (Grados M, Atkins E, Kovacikova GI, McVicar E. A selective review of glutamate pharmacological therapy in obsessive–compulsive and related disorders. Psychol Res Behav Manag 2015; 8: 115–31). It has been found to be safe, effective and well tolerated in treating skin-picking disorder and other compulsive disorders. Its beneficial effect appears to be a reduction in the urge to pick (Grant et al.). Our patient had suffered distress, pain and recurrent infections secondary to picking for over 20 years, and with NAC treatment has, for the first time, experienced an objective reduction in excoriations, and subjective improvement in itch and quality of life. This highlights the potential benefit of NAC for patients with compulsive skin-picking disorder.