Intralesional injection, the direct delivery of medication percutaneously into skin lesions, has been an important part of dermatologic therapy since first introduced in 1961 [1,2]. Intralesional injections are effective for a wide range of indications, are easily performed, and are relatively safe.
The rationale for intralesional therapy is simple: to deliver a medication directly into a specific skin lesion to treat local tissues with minimal systemic effects. The skin also serves as a reservoir, allowing medication deposited in the dermis to be delivered over a period of time, resulting in prolonged therapy while avoiding or minimizing the adverse effects of systemic therapy.
The drugs primarily used for intralesional injections are corticosteroids, but in recent years bleomycin, 5-fluorouracil, methotrexate, chloroquine, and interferons also have been dispensed in this manner . This review is limited to the use of intralesional corticosteroids.
Triamcinolone acetonide (Kenalog, TAC-3) and triamcinolone diacetate (Aristocort) are the most widely used intralesional corticosteroids, although dexamethasone (Decadron) and betamethasone (Celestone) are used by some physicians. Triamcinolone agents are available as micronized suspensions. Characteristics associated with micronized suspensions that make them desirable as intralesional corticosteroids are the small size of the corticosteroid particles, the persistence of small crystal size for extended periods of time, and that the process of gently shaking resuspends the drug evenly in solution. Small corticosteroid crystals are more efficiently delivered to the treatment site, thereby decreasing the total administered dose of the drug and reducing the risk of systemic side effects and skin atrophy. In addition, because micronized crystals of corticosteroid are in a depot form, the active ingredients are stored in the tissues and released over a period of weeks, making this type of corticosteroid delivery system well suited for the treatment of chronic inflammatory dermatoses . Examples of chronic inflammatory dermatoses that are particularly amenable to this type of extended action include psoriasis, lichen simplex chronicus, cutaneous lupus erythematosus, and prurigo nodularis.
INDICATIONS AND CONTRAINDICATIONS
Indications for intralesional corticosteroid therapy are acute and chronic inflammatory processes, hyperplastic and hypertrophic skin disorders, and conditions that typically have a favorable response to systemic and topical corticosteroids. In addition to antiinflammatory properties, the atrophogenic side effect of corticosteroids also can be used advantageously when treating hypertrophic types of lesions, including keloids, lichen simplex chronicus, hypertrophic lupus, and psoriasis.