Superficial X-ray-induced hyperpigmentation in postoperative keloid radiotherapy: A study of 70 keloids to identify clinical features and risk factors

Postoperative radiation is one of the most effective treatments for keloid. Radiation-induced hyperpigmentation is, however, a concern for both patients and dermatologists.

To identify clinical features and risk factors of superficial X-ray-induced hyperpigmentation in postoperative keloid radiotherapy.

From November 2019 to November 2020, 70 keloids in 55 patients were treated with superficial X-ray after surgery. Patient data and treatment-related parameters were collected. Follow-up photographs were taken one month after radiotherapy. Three independent dermatologists assessed photographs for pigmentation. The clinical characteristics and severity of pigmentation were summarized. Logistic regression was used to analyze the risk factors associated with occurrence and severity of hyperpigmentation.

The pigmentation was a well-defined rectangular brown macule consistent with the unprotected area that involves normal skin, and 82.9% of keloids displayed pigmentation induced by superficial X-ray at one month after treatment. All keloids of trunk appeared to be mild-to-moderately hyperpigmented (100%); 92.89% of limb keloids displayed mainly severe pigmentation. Keloid location was an independent risk factor for the incidence and severity of pigmentation. Longer incision length was also predictive of increased hyperpigmentation severity.

Superficial X-ray-induced hyperpigmentation was common and severe in postoperative keloid radiotherapy. The incidence and severity of pigmentation can be predicted by the location and incision length of the keloid.