Incidence of Bleomycin-Induced Hyperpigmentation in Patients Undergoing Sclerotherapy for Low-Flow Vascular Malformations

PURPOSE: To determine the incidence of bleomycin-induced hyperpigmentation in patients receiving bleomycin sclerotherapy for low-flow vascular malformations (LFVMs). MATERIALS AND METHODS: A retrospective chart review of patients with radiologically confirmed LFVM who had undergone ≥1 bleomycin sclerotherapy session. Treatments were performed at Vancouver General Hospital or British Columbia's Children's Hospital between January 2010 and September 2024. Incidence was calculated per patient and per session using exact binomial 95% CIs, and treatment and dosing variables were summarized descriptively. RESULTS: Hyperpigmentation occurred in 11 of 333 patients (3.3%; 95% CI, 1.7-5.8) across 11 of 701 treatment sessions (1.6%; 95% CI, 0.8-2.8). Affected patients included 6 females and 5 males. Reactions developed after 1, 2, or 3 treatments in 1.5% (5 of 333), 1.2% (2 of 164), and 3.4% (3 of 87) of sessions, respectively, with an additional case after ≥4 treatments (0.9%, 1 of 117). The overall cohort's median per-session and cumulative doses were 9 units (interquartile range [IQR], 9 units) and 12.5 units (IQR, 16.5 units), respectively. Among patients who developed hyperpigmentation, the median session dose prior to reaction was 11.3 units (IQR, 8 units), and the median cumulative dose at the time of reaction was 15 units (IQR, 21 units). All cases occurred without an adjunct sclerosant being administered. Hyperpigmentation involved multiple body regions in 8 patients, whereas 3 patients had isolated involvement, including 2 localized to the back and 1 to the hand. CONCLUSIONS: Bleomycin-induced hyperpigmentation was uncommon in LFVM sclerotherapy. These findings can inform patient consent and counseling on the risk of hyperpigmentation.