Intralesional steroid injection
Intralesional steroid injection involves a corticosteroid, such as triamcinolone acetonide or betamethasone suspension, which is injected directly into a lesion on or immediately below the skin.
In New Zealand triamcinolone is marketed as Kenacort-A, and is available in 2 strengths: 10 mg per ml (Kenacort-A 10), or 40 mg per ml (Kenacort-A 40). Triamcinolone acetonide is marketed as Kenalog in the USA. Betamethasone injection is marketed as Celestone Chronodose (1 mL).
Shorter-acting corticosteroid preparations, such as dexamethasone or betamethasone acetate, are sometimes administered in combination with triamcinolone.
What are intralesional steroids used for?
Intralesional steroid injection may be indicated for the following skin conditions:
- alopecia areata
- discoid lupus erythematosus
- keloids/hypertrophic scars
- granuloma annulare
- Other granulomatous disorders such as cutaneous sarcoidosis or granuloma faciale
- hypertrophic lichen planus
- lichen simplex chronicus (neurodermatitis)
- localised psoriasis
- necrobiosis lipoidica
- acne cysts (see nodulocystic acne)
- small infantile haemangiomas
- other localised inflammatory skin diseases
What are the advantages of intralesional steroids?
Intralesional administration of corticosteroids is used to treat a dermal inflammatory process directly. In contrast to topical steroids, intralesional steroids:
- bypass the barrier of a thickened stratum corneum
- reduce the chance of epidermal atrophy (surface skin thinning)
- deliver higher concentrations to the site of the pathology.
Other uses for triamcinolone acetonide injection
Triamcinolone is also sometimes used intramuscularly as an alternative to oral corticosteroids, for example for seasonal hay fever, or to treat a chronic skin disorder such as atopic dermatitis or lichen planus.
Typical intramuscular doses are 0.5–1 mg/kg body weight (40-80 mg for typical adult), which may be repeated every 30 days for 3 to 6 months.
Triamcinolone injections can also be used in the treatment of tendonitis, arthritis and synovitis.
Contraindications to intralesional steroid
They must not be used if there is a previous history of triamcinolone hypersensitivity (allergy).
When large doses of triamcinolone acetonide injections are used as an alternative to oral steroids such as prednisone, they are considered to be systemic steroids. These should be avoided in patients with the following disorders.
- Active tuberculosis or systemic fungal infections
- Extensive plaque psoriasis, pustular psoriasis or erythrodermic psoriasis – systemic steroids may destabilise condition
- Active peptic ulcer disease
- Uncontrolled diabetes, heart failure or severe hypertension
- Severe depression or psychosis
Administration of intralesional steroid
Intralesional triamcinolone is injected directly into the skin lesion using a fine needle after cleaning the site of injection with alcohol or antiseptic solution. The injection should be intradermal, not subcutaneous, to avoid causing a dent in the skin.
The initial dose per injection site will vary depending on the lesion being treated. Generally, 0.1–0.2 mL is injected per square centimetre of involved skin. The total dose should not normally exceed 1 or 2 mL per dose. It can be repeated every 4 to 8 weeks.
The corticosteroid can be full strength (eg triamcinolone 10 mg/mL or 40 mg/mL) or diluted with normal saline or local anaesthetic. Typical regimes for triamcinolone intralesional injections include:
- 40 mg/mL for a thick keloid scar
- 10 mg/mL for a moderate thickness hypertrophic scar
- 10 mg/ml into discoid lupus erythematosus or granuloma annulare
- 5 mg/ml into skin of normal thickness associated with alopecia areata.
The injections may be repeated monthly for a few months while the lesions are active.
Side effects arising at the site of intralesional steroid injection
Side effects and risks of intralesional triamcinolone may be separated into early and delayed effects.
Early effects tend to be self-limited. They include:
- Pain, bleeding, bruising
- Contact allergic dermatitis due to the preservative, benzyl alcohol
- Impaired wound healing
- Sterile abscess, sometimes requiring surgical drainage
Delayed adverse effects include:
- Cutaneous and subcutaneous lipoatrophy (most common) appearing as skin indentations or dimples around the injection sites a few weeks after treatment; these may be permanent.
- White marks (leukoderma) or brown marks (postinflammatory pigmentation) at the site of injection or spreading from the site of injection – these may resolve or persist long term.
- Telangiectasia, or small dilated blood vessels at the site of injection. These can be treated if necessary by laser or intense pulsed light (IPL).
- Increased hair growth at the site of injection (localised hypertrichosis) – this resolves eventually.
- Localised or distant steroid acne: steroids increase growth hormone, leading to increased sebum (oil) production by the sebaceous glands. Steroid acne generally improves once the steroid has been stopped.
Systemic side effects of triamcinolone injections
Allergic reactions are very rare, and dose independent but may include local or generalised urticaria (wheal and flare), and in more severe cases, anaphylaxis (angioedema, swollen face/tongue, respiratory distress, hypotension/shock).
Other systemic side-effects are not likely to follow intralesional injection of localised skin disease because the dose used is very small.
However, the following potentially serious conditions have been reported from intramuscular injection of large doses of triamcinolone acetonide.
- Heart: congestive heart failure in susceptible patients, fluid retention, hypertension, cardiac arrhythmias.
- Hormones: decreased glucose tolerance, Cushing syndrome, hirsutism, hypertrichosis, manifestations of latent diabetes mellitus, menstrual irregularities, adrenocortical and pituitary unresponsiveness, suppression of growth in children.
- Musculoskeletal: aseptic necrosis of hip or shoulder bones, calcinosis, osteoporosis and pathological fractures, muscle weakness, tendon rupture.
- Neurologic/psychiatric: convulsions, depression, euphoria, swelling of the brain, insomnia, mood swings.
- Eyes: glaucoma, cataracts, rare instances of blindness associated with periocular injections.