Intralesional Injection Technique: Triamcinolone and 5-FU

Overview / Definition Intralesional injection is a technique in which a medication is injected directly into a lesion or affected area of the skin. This method allows for higher local concentrations of the drug, leading to more effective treatment outcomes. Triamcinolone acetonide is a synthetic corticosteroid commonly used to reduce inflammation, while 5-fluorouracil (5-FU) is a chemotherapeutic agent effective in treating certain skin tumors and conditions. Epidemiology The use of intralesional injections is widespread in dermatology. Conditions treated include: Dermatofibromas Keloids Psoriasis Basal cell carcinoma Actinic keratosis The prevalence of conditions treated with intralesional injections varies globally, but these injections are a standard practice across dermatologic practices. Pathophysiology / Mechanism Triamcinolone works by inhibiting the inflammatory response through several mechanisms, including: Suppressing the migration of leukocytes Inhibiting the release of inflammatory mediators Reducing collagen synthesis 5-FU acts by interfering with DNA synthesis and inhibiting the enzyme thymidylate synthase, leading to the cytotoxic effects on rapidly dividing cells, such as those found in certain skin lesions. Clinical Presentation Lesions treated with intralesional injections may present as: Raised and inflamed areas (e.g., keloids) Thickened skin (e.g., dermatofibromas) Red, scaly patches (e.g., actinic keratosis) These characteristics aid in the selection of the appropriate treatment and the medication to be used. Diagnosis / Workup Diagnosis typically involves a thorough patient history and physical examination. Biopsy may be indicated for: Uncertain diagnosis Lesions that do not respond to initial treatments Imaging is rarely necessary unless there is concern for deeper involvement of the disease. A dermatopathologist may assist in the diagnosis of suspicious skin lesions. Treatment / Management Intralesional injection techniques involve the foll