A Case of Doxycycline-induced Melanin in the Gingiva Tissue: Case Report.

Background: Gingival pigmentation is a discoloration of the gingiva due to a variety of lesions and conditions associated with several endogenous and exogenous etiologic features.

Objective: The purpose of this study is to describe a report of gingival pigmentation in a patient who used doxycycline.

Case Report: A 21-year-old Caucasian female was under dermatological treatment and antibiotic therapy with doxycycline 100 mg (one time a day) for 90 days. She presented brown pigmentation at the gingival margin on the facial surfaces of the upper and lower anterior incisors and premolars. The patient was evaluated by immunohistochemical (S-100, Melan-A, and HMB-45) and histopathologic analyses, and clinical history. Blood levels of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were analyzed by UV/Vis spectroscopy. The adrenaline, noradrenaline, and dopamine in blood were analyzed by high-performance liquid chromatography (HPLC); dehidroepiandrosterone (DHEA) in serum by radioimmunoassay; and luteinizing hormone (LH) and 25-Hydroxyvitamin D by chemiluminescence. Hematoxylin-eosin stained sections revealed keratinocytes with pigment compatible with melanin. The Fontana-Masson staining was positive in melanophages and in some basal keratinocytes. S-100, Melan A and HMB-45 were confirmed as positive markers of melanocytic differentiation in gingival tissue. We observed a significant increase in malondialdehyde (p˂0.05) and a decrease in superoxide dismutase levels (p˂0.05). The dopamine value was found to be 15 pg/ml (reference value ≤ 10 pg/ml).

Conclusion: The use of doxycycline is associated with an increase in oxidative stress and of dopamine with melanin pigments in the gingival tissue. This case report showed a cause-effect relationship between exposure to doxycycline and pigmentation of the marginal gingiva.