title: Histological Features of Methylene Blue-Induced Phototoxicity Administered in the Context of Parathyroid Surgery.
abstract: Methylene blue is a chromophore dye known for its photosensitizing properties. It is also administered intravenously as a tracer in parathyroid surgery to identify abnormal glands. We describe 2 cases of acute methylene blue-induced phototoxicity in patients who underwent parathyroidectomy. Both patients developed an acute vesiculopustular inflammatory rash on the anterior neck corresponding to the site exposed intraoperatively to overhanging surgical lights. One of the patients also developed a bulla on her finger at the site of attachment of the oxygen probe. Biopsies were taken from both patients at different time points. The histological findings included destruction of sebaceous glands and deposition of diastase-periodic acid-Schiff-positive hyaline material around dermal blood vessels. These features are similar to those seen in skin treated with photodynamic therapy and systemic photosensitivity disorders such as the porphyrias. The wavelengths of light emitted by the surgical lights and oxygen probe overlap with the absorption spectrum of methylene blue. This resulted in excitation of the systemically administered methylene blue at exposed sites, with resultant local tissue damage and a phototoxic reaction.
authors.affiliation: Departments of *Dermatology, †Breast and Endocrine Surgery, and ‡Cellular Pathology, St George's University Hospital, London, United Kingdom.
authors.forename: Ciara A
authors.initials: CA
authors.lastname: Maguire
authors.forename: Anup
authors.initials: A
authors.lastname: Sharma
authors.forename: Lida
authors.initials: L
authors.lastname: Alarcon
authors.forename: Lorrette
authors.initials: L
authors.lastname: Ffolkes
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Kurzepa
authors.forename: Lucy
authors.initials: L
authors.lastname: Ostlere
authors.forename: Venura
authors.initials: V
authors.lastname: Samarasinghe
authors.forename: Manuraj
authors.initials: M
authors.lastname: Singh
mesh_terms: D000328:Adult; D004396:Coloring Agents / Q000009:adverse effects*; D017484:Dermatitis, Phototoxic / Q000473:pathology*; D005260:Female; D006801:Humans; D008751:Methylene Blue / Q000009:adverse effects*; D008875:Middle Aged; D010282:Parathyroid Neoplasms / Q000601:surgery; D016105:Parathyroidectomy / Q000379:methods*
chemical_list: D004396:Coloring Agents; D008751:Methylene Blue