Introda significant: Onychomycosis is the most common nail disorder seen in clinical practice, and it may have significant impact on patient quality of life. Understanding risk factors for onychomycosis may help to devise screening and treatment guidelines for populations that are more susceptible to this infection. Using a national database, we aimed to explore associations between onychomycosis and age, sex, and underlying medical conditions, as well as to examine current onychomycosis treatment trends. Materials and Methods: We performed a nested, matched, case-control study of patients in the All of Us database aged ≥ 18 years (6 May 2018-1 January 2022). Onychomycosis cases were identified using International Classification of Diseases (ICD) and Systematized Nomenclature of Medicine (SNOMED) diagnostic codes (ICD-9 110.1, ICD-10 B35.1, SNOMED 414941008). Demographic information (i.e., age, sex, and race), treatments, and co-diagnoses for onychomycosis patients and case-controls were recorded. Wald\'s test applied to multivariate logistic regression was used to calculate odds ratios and p-values between onychomycosis and co-diagnoses. Additionally, 95% confidence intervals were calculated with a proportion test. Results: We included 15,760 onychomycosis patients and 47,280 matched controls. The mean age of onychomycosis patients was 64.9 years, with 54.2% female, 52.8% Non-Hispanic White, 23.0% Black, 17.8% Hispanic, and 6.3% other, which was similar to controls. Patients with onychomycosis vs. controls were more likely to have a co-diagnosis of obesity (46.4%, OR 2.59 [2.49-2.69]), tinea pedis (21.5%, OR 10.9 [10.1-11.6]), peripheral vascular disease (PVD) (14.4%, OR 3.04 [2.86-3.24]), venous insufficiency (13.4%, OR 3.38 [3.15-3.59]), venous varices (5.6%, OR 2.71 [2.47-2.97]), diabetes mellitus (5.6%, OR 3.28 [2.98-3.61]), and human immunodeficiency virus (HIV) (3.5%, OR 1.8 [1.61-2.00]) (p < 0.05, all). The most frequently prescribed oral and topical medications were terbinafine (20.9%) and ciclopirox (12.4%), respectively. The most common therapeutic procedure performed was debridement (19.3%). Over the study period, ciclopirox prescriptions (Spearman correlation 0.182, p = 0.0361) and fluconazole prescriptions increased (Spearman correlation 0.665, p = 2.44 × 10-4), and griseofulvin (Spearman correlation -0.557, p = 0.0131) and itraconazole prescriptions decreased (Spearman correlation -0.681, p = 3.32 × 10-6). Conclusions: Our study demonstrated that age, obesity, tinea pedis, PVD, venous insufficiency, diabetes mellitus, and HIV were significant risk factors for onychomycosis. In addition, the most frequent oral and topical onychomycosis medications prescribed were terbinafine and ciclopirox, likely reflective of efficacy and cost considerations. Identifying and managing these risk factors is essential to preventing onychomycosis\' primary infections and recurrences and improving treatment efficacy.

There is a lack of efficacious topical treatments for patients suffering from psoriatic nail disease (PND). We investigated the efficacy of Calcipotriol-Betamethasone Dipropionate (Cal/BD) foam with and without ablative fractional laser (AFL) in patients with PND. A total of 144 nails from 11 patients were treated in a 24-week long, open-label, randomized, intra-patient controlled proof-of-concept hybrid trial. In addition to daily Cal/BD foam application, half of each patient\'s psoriatic nails were randomized to receive optical coherence tomography (OCT)-guided AFL treatment at baseline, 6-, and 12-week follow-ups. In-clinic assessment (N-NAIL), patient-reported outcomes (PROMs), and drug consumption were supplemented by remote evaluation of 15 subclinical OCT features, smartphone app-based safety monitoring, and photo-based assessment (NAPSI). After 24 weeks of Cal/BD foam treatment, patients achieved a significant improvement (p < 0.001) in both clinical (N-NAIL -76%, NAPSI -68%) and subclinical (OCT -43%) PND severity as well as a 71% reduction in PROMs. AFL-assisted Cal/BD treatment led to higher clinical (N-NAIL -85%, NAPSI -78%) and OCT-assessed (-46%) reduction of PND signs than Cal/BD alone (N-NAIL -66%, NAPSI -58%, OCT -37%), but did not reach statistical significance. Smartphone app images documented adverse events and mild local skin reactions, particularly erythema (75%), laser-induced swelling (28%), and crusting (27%). This hybrid trial demonstrated a reduction in clinical NAPSI and N-NAIL scores, subclinical OCT features, and PROMs, suggesting that Cal/BD foam is a safe and efficacious treatment for PND. Larger trials are warranted to prove the clinical benefit of AFL pretreatment as a Cal/BD delivery enhancer.

Noninvasive techniques for nail imaging would be useful for confirming diagnosis and monitoring treatment response at the microscopic level in patients with nail psoriasis. However, the use of ultrasound and high-resolution magnetic resonance imaging in nail evaluation is limited. Optical coherence tomography (OCT) produces high-resolution images of transversal tissue sections and represents an optimal approach to the study of the nail. This study used a multibeam OCT instrument to produce speckled variance OCT (SV-OCT) blood-flow images, which were used to measure the degree of change over successive scans. Nail changes, inflammation and response to therapy were evaluated in a 75-year-old female patient with psoriasis who had severe acrodermatitis continua of Hallopeau of the hands, treated for 4 weeks with 40 mg adalimumab (administered subcutaneously every other week) and 25 mg prednisone (administered orally, daily). SV-OCT provided a detailed assessment of the nail structures in relation to inflammation of psoriatic tissues. Restoration of the normal anatomy of the nail apparatus was apparent following adalimumab treatment; SV-OCT evaluation correlated with clinical appearance. SV-OCT may have a diagnostic role and provide an objective tool to assess clinical and subclinical inflammation in nail psoriasis.

Photodynamic therapy (PDT) is a medical modality that uses a combination of visible light and a photosensitive compound in the presence of oxygen. It is widely used to treat non-melanoma skin cancer; other indications are being investigated, especially onychomycosis. Eighty patients with toenail onychomycosis were enrolled and completed this randomized, parallel, placebo-controlled study. For 24 weeks, 40 patients (Group A) were treated with one placebo capsule per week and sessions of 2% methylene blue aqueous solution irradiated with light emission diode device (MBLED/PDT) with 18 J/cm(2) ; and another 40 patients (Group B) were treated with 300 mg oral fluconazole per week and sessions of placebo PDT (haematoxylin-diluted 1 : 10). The use of MBLED/PDT consisted of sessions with an interval of 15 days between each session for 6 months. Microbiological and clinical cure was assessed at 1 and 12 months posttreatment. Group A (MBLED/PDT) patients showed a significant response (p < 0.002) compared with Group B (fluconazole), especially in patients who required nail abrasion (p < 0.001). The MBLED/PDT is safe, effective, and well tolerated; it promotes a favorable outcome with good patient adherence and may be considered as a practical and feasible treatment option for toenail onychomycosis.