Keloid after a BCG vaccination

The vaccine site normally heals through inflammation and scar formation. In a keloid, scar-producing cells continue laying down collagen beyond the boundary of the original skin injury. This is different from a hypertrophic scar, which stays within that boundary.

A keloid usually feels firm and rises above the surrounding skin. Its surface may be smooth, and its colour may differ from nearby skin. Growth can continue after the injection wound has closed, sometimes creating a shape wider than the original mark.

A clinician usually diagnoses it from its appearance, texture and history. A lesion that is unusually inflamed, draining, ulcerated or diagnostically uncertain may need a different assessment because infection, cysts and other skin lumps can mimic scar tissue.

Protect the area from repeated rubbing and avoid cutting, needling or tying off the scar yourself. If it is stable and not troublesome, observation may be reasonable. If itch, tenderness, movement restriction or continuing growth is a concern, a dermatologist can tailor treatment to its thickness, activity and location.

Options may include steroid injected into the scar, freezing treatment or selected laser procedures. Surgical removal can be considered for some keloids, but excision creates a fresh wound that may form another keloid; clinicians therefore often discuss an accompanying plan intended to limit regrowth.

Book a medical review if the scar is continuing to enlarge, becomes increasingly painful, restricts shoulder movement or has an uncertain diagnosis. Prompt assessment is also appropriate for new breakdown of the surface, persistent drainage or recurrent bleeding.

Seek urgent care if redness rapidly spreads away from the site, swelling becomes severe, pus appears with fever or you feel systemically unwell. Those findings point to an active complication rather than uncomplicated scar overgrowth.

Ask how certain the diagnosis is, whether the keloid is still active and which option targets your main concern. Discuss expected skin-colour changes, wound care, the possibility of recurrence, whether combined treatment is appropriate and how progress will be judged.