Interdigital neuroma. Local cutaneous changes after corticosteroid injection.

Interdigital neuroma was diagnosed in a patient who was treated subsequently with a local corticosteroid injection. Two to 3 weeks after injection, a 2.5 x 1.5-cm area of hyperpigmentation, thinning of the skin, and subcutaneous fat atrophy developed at the site of the injection. Occurrence of these side effects depends on the solubility of the steroid preparation, the dosage, and the anatomic site and depth of the injection. When using local corticosteroid injections to treat interdigital neuromas, the physician should be familiar with the properties and recommended dosage of the given steroid. The injection should be deep enough so that the cortisone solution does not leak into the subcutaneous area. The possibility of skin atrophy and altered pigmentation should be discussed with all patients.