Nail Unit Injections for Inflammatory Nail Disorders

Conclusions

• Intralesional injections are an effective treatment for nail-unit inflammatory disorders, especially when only a few nails are involved or systemic therapy is unsuitable.
• Successful treatment depends on identifying whether the pathology is in the nail matrix, nail bed, or proximal fold, so the injection must be placed at the site of the inflammatory infiltrate.
• Needle-based injection with a thin needle and Luer-lock syringe is preferred, while jet injectors like Dermojet should be avoided because they can cause uncontrolled depth and permanent nail dystrophy.
• Pain control is important, and anesthesia is particularly mandatory for injections into the nail bed.
• Triamcinolone acetonide is the main drug used, and lower concentrations appear to work as well as higher ones, allowing dose reduction to limit adverse effects.
• Common side effects include hematoma, transient growth arrest, Beau’s lines, and occasional focal skin atrophy, but serious complications are uncommon when technique is proper.
• Intralesional steroid injections appear especially effective for hyperkeratosis and psoriasis, with more variable responses for pitting and onycholysis.
• The technique can also be used in children and in conditions such as chronic paronychia and mild-to-moderate retronychia, though lower doses are needed in pediatric patients.
• Methotrexate may be an alternative to triamcinolone with similar efficacy and fewer steroid-related side effects in some settings.
• Myxoid pseudocysts should not be treated with sclerosing agents because of the risk of permanent nail damage, and steroid injection for these lesions has a substantial recurrence rate.
• Overall, the key message is that intralesional nail injections are highly useful when the diagnosis is correct, the target site is chosen carefully, and dosing and anesthesia are handled conservatively.