Revealing the origin of postsclerotherapy hyperpigmentation: Identification of melanin and hemosiderin as causative pigments in a histopathological study.

IntroductionPostsclerotherapy hyperpigmentation (PSH) is a common side effect of sclerotherapy that can persist in a small proportion of patients. Up to now, hemosiderin has been the only histologically proven causative pigment, making laser treatment the primary therapeutic option.ObjectivesThe aim of the study was to identify the origin of pigment in post-sclerotherapy hyperpigmentation based on histopathological findings.MethodsWe analyzed 20 skin biopsies from 19 patients including identification of the type of pigment and pigment location. 10 biopsies were taken from patients with PSH >3 months and 10 from those with PSH <3 months. The analyses included hematoxylin-eosin, Prussian blue, Masson-Fontana and CD68 staining.ResultsHemosiderin was detected in all biopsies, predominantly in the reticular dermis and in the subcutis, with a particular prevalence in newer PSH cases. Epidermal melanin was enhanced in three patients, whereas dermal melanin was increased in seven patients, three of whom also exhibited a decrease in epidermal pigment.ConclusionHemosiderin and postinflammatory hyperpigmentation with increased dermal or epidermal melanin contribute to the development of PSH in some patients.