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Author: Dr Tim Aung, Primary Care Practitioner, Brisbane, Queensland, Australia. DermNet NZ Editor-in-Chief: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. January 2020.
An intralesional injection is the direct injection of a therapeutic substance into a lesion or into the skin. The aim of an intralesional injection is to deliver a higher concentration of medicine into the site of the pathology to maximise efficacy while minimising systemic adverse effects of the drug.
The most common medication used for intralesional injection is a corticosteroid such as triamcinolone acetonide.
Intralesional steroid is used for localised inflammatory, hyperplastic and hypertrophic lesions [1,2].
Other drugs that are sometimes injected into other skin lesions include 5-fluorouracil (eg, for keloid scar) , bleomycin (eg, for viral wart) , methotrexate (eg, for nail psoriasis) , rose Bengal, and interferon (see Topical and intralesional immunotherapy for melanoma metastases).
Cosmetic use of injected medications include:
It should not be used if the patient is allergic to the specific drug .
Intralesional injections may not be suitable for widespread or extensive lesions.
Triamcinolone acetonide is widely available with 10 mg/mL or 40 mg/mL strengths marketed in Australasia. The dose depends on the type, size, and location of the lesion.
0.1–0.2 mL is injected per square centimetre of involved skin. The steroid can be diluted with normal saline or plain local anaesthesia.
A Luer-lock syringe (figure 1) or an insulin syringe can be used with a 25 to 30-gauge needle, or a special syringe set with a controlled depth needle can be used (eg, Dermojet). Otherwise, the medicine may spill if the needle disconnects from the syringe due to the resistance of dense collagen tissue. Insert the needle at a 10 to 20-degree angle for a flat lesion (figure 2), or at an increased angle for a raised lesion. A subcutaneous injection should be avoided.
The procedure can be repeated every 4–6 weeks for 2–3 cycles or longer.
Figure 2 Credit: McGraw Hill Education; used with permission.
An intralesional injection is a painful procedure even when mixed with local anaesthesia, as numbing occurs a few minutes later. Tips for minimising pain are:
An intralesional injection is a simple office-based and relatively safe procedure with proven benefits in specific skin conditions.
The possible side effects of intralesional injection of a corticosteroid are:
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