LAUSR

Pityriasis rubra pilaris (PRP) is a rare papulosquamous inflammatory dermatosis of unknown origin and wide clinical heterogeneity. Its cardinal clinical features are hyperkeratotic follicular papules, orange-red scaling plaques, and palmoplantar hyperkeratosis, and it frequently progresses to generalised erythroderma. The most frequent form of PRP in adults is type 1 according to the widely used classification of Griffiths. We report the case of a 61-yearold woman with refractory PRP successfully treated by apremilast administration. A 61-year-old woman presented with a 3-month history of generalised pruritic eruption. It started as large erythematous scaly patches and plaques on her scalp and trunk, with cephalo-caudal spread and islands of sparing. She also had hyperkeratotic scaling of her palms and soles. She underwent oral corticosteroid treatment without improvement and progression to erythroderma (Figure 1A). Skin biopsy showed epidermal acanthosis, alternating orthokeratosis and parakeratosis, and dermal lymphohistiocytic infiltrate with few neutrophils. There was no historical or current evidence of an active infectious event, including human immunodeficiency virus (HIV) infection. Before onset of the PRP, she had not taken any new medication. No signs of comorbidity were found in routine clinical and laboratory examinations. Finally, type 1 PRP was diagnosed. After 1 month of acitretin administration (35 mg/d) with no significant or lasting effect, the patient was treated with various therapeutic regimens, given more than 3 months, including methotrexate, adalimumab, and cyclosporine, observing no improvement. After informed consent was obtained, treatment was started with apremilast (30 mg twice daily) following the recommended titration schedule. A marked improvement was observed, with almost complete clearance of the pruritus and erythema at 2 months of apremilast treatment (Figure 1B), which was discontinued after 7-month follow-up with no recurrence of PRP lesions. Three months later, the patient was completely free of symptoms. The therapeutic approach to PRP is mainly based on anecdotal clinical observations, given the absence of a controlled clinical trial, generating uncertainty about the true effectiveness of treatments. Besides systemic retinoids and methotrexate, generally considered first-line treatments, cyclosporine, azathioprine, phototherapy, fumaric acid, and various biological therapies have been applied over the past decade; all of these have been described as effective in isolated case reports or small case series, mostly consisting of difficult-to-treat patients. Apremilast is a small molecule that inhibits phosphodiesterase-4 and increases intracellular cyclic adenosine monophosphate levels, thereby reducing levels of proinflammatory cytokines (eg, tumour necrosis factor–α, interleukin [IL]–23, and interferon-γ) and increasing levels of anti-inflammatory cytokines (eg, IL-10). Based on these effects, apremilast has been proven to be a promising agent in the management of chronic inflammatory diseases, including psoriasis and psoriatic arthritis. There has been 1 case report on the successful use of apremilast against PRP, which can be clinically and histologically similar to psoriasis. We therefore offered a trial of this drug to our patient, whose type 1 PRP had proven recalcitrant to several conventional and novel therapies. We cannot completely rule out the possibility of a spontaneous remission of PRP in this case. However, apremilast therapy was started during a severe phase of erytrodermic PRP, and the prompt and major improvement in PRP lesions suggests that the treatment was more likely to have been responsible for the outcome. We highlight that apremilast was well tolerated by our patient, with no significant adverse effects. The response to apremilast observed in the present patient and in the previous report suggests that this drug may be an Medical Letter 733464 CMSXXX10.1177/1203475417733464Journal of Cutaneous Medicine and SurgeryMolina-Figuera et al letter2018