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516 REVIEW ARTICLE Nail Psoriasis: An Updated Review and Expert Opinion on Available Treatments, Including Biologics Federico BARDAZZI, Michela STARACE, Francesca BRUNI, Michela MAGNANO, Bianca Maria PIRACCINI and Aurora ALESSANDRINI Division of Dermatology, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Italy Nail psoriasis affects 50–79% of patients with skin psoriasis and up to 80% of patients with psoriatic arthritis, and can also represent a negative prognostic factor in individuals with plaque psoriasis. Treatments for nail psoriasis are limited, as nails are often diffi- cult to treat with topical therapies alone, and relapse is common. Among different systemic agents, secukinu- mab, a fully human monoclonal antibody targeting interleukin (IL)-17A, is the only antibody supported by a trial specifically conducted in patients with nail psoriasis (the TRANSFIGURE trial) and has the longest follow-up available to date. In this setting, secukinu- mab is characterized by the highest efficacy at week 16. This review analysed the different therapeutic op- tions for nail psoriasis, focusing on new treatments that have shown promising results in this field. Key words: biologic therapy; efficacy; nail psoriasis; systemic therapy; tolerability. Accepted Dec 6, 2018; E-published Dec 6, 2018 Corr: Aurora Alessandrini, Department of Experimental, Diagnostic and Specialty Medicine - Division of Dermatology, University of Bologna, Bo- logna, Italy, Via Massarenti, 1, IT-40138 Bologna, Italy. E-mail: aurora. [email protected] ail psoriasis affects 50–79% of patients with skin psoriasis and up to 80% of patients with psoriatic arthritis (1). The nail matrix or nail bed can be involved by the disease, inducing aesthetic problems and functio- nal damage to patients (2). Clinical manifestations are typical when they involve fingernails, while they can be confusing when the toenails are affected, as they can include subungual hyperkeratosis, which is also a ma- nifestation of onychomycosis. Differential diagnosis is therefore very important in choosing the most appropriate treatment. Diagnosis is based on clinical manifestations, but, in some cases, nail dermoscopy can help the phy- sician to better visualize the alterations not visible to the naked eye. Where diagnosis is uncertain, a biopsy may be mandatory. The severity of the disease is defined by a validated score, the Nail Psoriasis Severity Index (NAPSI), which is a useful tool for deciding the best treatment and for monitoring the response. The treatment of nail psoriasis is not standardized, ranging from topical therapy to sys- temic therapy, according to the severity and extension of the disease. Biologic therapies have also been introduced doi: 10.2340/00015555-3098 Acta Derm Venereol 2019; 99: 516–523 Nail psoriasis frequently affects patients with skin psoria- sis, inducing not only aesthetic problems, but also functio- nal damage. The disease represents a significant burden, impairing patients’ quality of life. The treatment of nail pso- riasis varies according to disease severity. Topical therapies are used if the nail involvement is mild, but their efficacy is limited and relapses are common. In more serious cases, systemic agents (both traditional and biologic molecules) have shown long-term efficacy. Among biologics, secukinu- mab is the only agent supported by evidence from a trial specifically conducted in patients with nail psoriasis. as a treatment option for nail psoriasis, although it is still not clear which is the most effective to treat this particular psoriatic localization. EPIDEMIOLOGY Acta Derm Venereol 2019; 99: 516–523. N SIGNIFICANCE Psoriasis is a chronic inflammatory disease affecting up to 3% of the general population. The prevalence of nail involvement ranges between 15% and 79% (1, 3–5). Nail psoriasis is less common in children, where the prevalence is 7–13%, while in adults it is more com- mon, even in the absence of skin and joint involvement, reaching a prevalence of 5–10%. Approximately 90% of patients with psoriasis develop nail psoriasis during their life, and it does not appear to be related to the sex or age of the patient (6). CLINICAL MANIFESTATIONS Clinical manifestations of nail psoriasis depend on the affected site of the nail, which can be the nail matrix, the nail bed, the proximal nail fold or the hyponychium (7). All nails or only a few fingernails or toenails can be involved (Fig. 1A–C). When the disease affects the nail matrix, the most severe nail changes are observed, and include pitting, lunulae red spots and nail plate crumbling. Pitting is a very characteristic manifestation of nail psoriasis, and is diagnosed by the presence of small depressions on the nail plate surface. The pathogenetic mechanism of pitting is due to a focal defect of keratinization of the proximal matrix, with persistence of nucleated and incompletely keratinized (parakeratotic) cells within the upper layers This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.