Corticosteroid injections are a common medical procedure used to reduce inflammation in joints, tendons, and other soft tissues. While highly effective for managing pain, a temporary indentation or lump at the injection site is a recognized side effect that can cause alarm. This reaction is usually harmless and often temporary, resulting from the local effect of the medication on the tissue beneath the skin. Understanding the nature of this lump and the available management options can provide reassurance.
Identifying the Post-Injection Lump
The lump or indentation that appears after a steroid injection is most frequently caused by lipoatrophy, which involves the localized loss of subcutaneous fat tissue. Corticosteroids are potent anti-inflammatory agents. When concentrated in one area, they can disrupt adipocytes (the cells that store fat), causing the breakdown of the fat pad beneath the skin and resulting in a depression or dimpling on the surface.
The physical manifestation of lipoatrophy is generally a cosmetic concern, presenting as a soft, painless divot rather than a hard lump. This atrophy occurs because the crystalline structure of the injected steroid can precipitate in the tissue, leading to a localized reaction that targets fat cells. It typically develops gradually, often becoming noticeable two to three months following the injection.
The incidence of this side effect is relatively low, occurring in less than 1% to 5.8% of local steroid injections. It is more common when the medication is injected too superficially into the fat layer. This localized tissue reaction is distinct from a painful, firm lump that might appear immediately due to the volume of fluid injected or a hematoma.
Management Strategies for Lipoatrophy
The primary strategy for managing steroid-induced lipoatrophy is observation and patience, as the condition is often self-resolving over time. The body’s natural processes work to regenerate lost fat and collagen, and the indentation typically begins to improve within six to twelve months. The majority of cases eventually correct themselves without intervention.
Localized stimulation can be applied to encourage better circulation while waiting for the tissue to regenerate. Gentle massage of the site, once initial soreness has subsided, helps disperse any remaining steroid crystals and promotes blood flow, supporting tissue repair. Applying a warm compress or heat to the area after the first 48 hours can also increase local circulation.
For more pronounced or persistent cases, a physician may suggest office-based medical interventions. One accessible option is the use of serial intralesional injections of sterile saline solution into the depressed area. The saline helps to re-dissolve or redistribute the concentrated steroid crystals, encouraging the fat cells to recover their function.
More advanced treatments are available for indentations that fail to resolve after a year. These physician-led procedures include the use of hyaluronic acid dermal fillers or poly-L-lactic acid to temporarily restore volume and stimulate collagen production. Structural fat grafting, which involves harvesting fat from another part of the patient’s body and injecting it into the atrophied area, is an effective, though more invasive, option for permanent correction.
Knowing When Medical Attention is Necessary
While lipoatrophy is generally a cosmetic issue, any lump or change at an injection site must be monitored for signs of a more serious complication. Immediate medical evaluation is necessary if the lump is accompanied by indicators of an infection, such as:
- Increasing pain that lasts more than 48 hours.
- Spreading redness.
- Significant warmth.
- Swelling around the injection site.
A fever, chills, or the presence of pus or drainage from the site strongly suggests a localized infection, which requires prompt treatment. Any lump that appears immediately and is painful or deeply bruised may indicate a hematoma, a collection of blood under the skin, which should be assessed by a healthcare provider.
Systemic symptoms also warrant urgent medical attention, as they could signal a severe reaction or the spread of infection:
- Feeling generally unwell.
- A spreading rash.
- Difficulty breathing.
- Sudden changes in vision.
Diabetics should also monitor their blood sugar closely, as corticosteroids can temporarily cause elevated glucose levels for up to a week following the injection.