Brilliant Green Staining of the Fingernails

Case Report

A 92-year-old Eastern European woman presented to our nail clinic with a history of onychodystrophy and arthralgia of the digits of several months’ duration. Her dermatologic history was notable for irritant hand dermatitis. A prior nail plate clipping with histopathologic examination was negative for fungal elements. Physical examination revealed onychorrhexis of all fingernails as well as onycholysis and subungual hyperkeratosis of the right fourth fingernail. Blue-green staining was incidentally noted on the right second and third fingernails and nail folds (Figure 1). Contact dermoscopy using ultrasound gel revealed translucent areas with sparse pigment, though denser areas had a fine branching pattern (Figure 2). When questioned, the patient reported use of “zelyonka,” a brilliant green solution, to self-treat the nails. Histopathology on repeat nail clippings showed parakeratosis and serum, which was most consistent with her known history of irritant hand dermatitis. Radiographs of the hands revealed osteoarthritis that was most prominent at the distal interphalangeal joints.

Figure 1. Blue-green staining on the right second and third fingernails and nail folds from use of brilliant green to self-treat onychodystrophy.

Figure 2. Contact dermoscopy showed translucent areas with sparse pigment and denser areas with a fine branching pattern.

Comment

Brilliant green is a triphenylmethane dye commonly used in Eastern Europe and other regions for the treatment of superficial skin infections and onychomycosis.¹ Its use as an antiseptic and wound healing agent has been investigated in the scientific literature since at least the early 20th century.² Brilliant green typically is applied in a 0.1% to 2% ethanol solution.¹ The dye has bactericidal activity against gram-positive organisms, particularly staphylococci and streptococci.^2,3 It has been used for the treatment of fungal skin and nail infections since at least the early 20th century, with anecdotal success.⁴ Although there have been no studies investigating use of brilliant green alone for the treatment of onychomycosis, it is sometimes used in combination with conventional oral agents for this purpose.⁵ Because of its availability, safety, ease of use, and low cost, brilliant green has been promoted as an antiseptic in resource-poor settings.³ The revival of brilliant green and other antiseptic dyes in these settings has been suggested as an alternative to oral antibiotic agents, to which resistance is rising, and as a potential cancer therapy.^6,7 Although brilliant green’s mechanism of action in treating skin infections is unclear, it has been shown to form covalent adducts with thioredoxin reductase 2, a protein conserved from bacteria to humans with an essential function for cellular activity.⁷

Early case studies suggested that brilliant green was beneficial in treating wounds²; however, this indication is controversial. In a guinea pig study, brilliant green was shown to inhibit wound healing and the formation of granulation tissue.⁸ It also should be noted that when used topically, brilliant green may cause skin sensitization, necrotic skin reactions, and permanent staining of clothing. It has no known anti-inflammatory properties and also may cause skin irritation.⁸ Brilliant green may cause blindness if it comes in contact with the eyes.¹

Brilliant green has other potential dermatologic indications. For example, a combination of brilliant green and gentian violet, a related dye, has demonstrated efficacy in the treatment of cutaneous hemangiomas in mouse models by blocking expression of angiopoietin-2.⁷

Dermatologists should be familiar with brilliant green and its common uses as well as adverse effects. Brilliant green is commercially available for a low cost ($5 to $20) in specialty pharmacies or online (eg, Amazon). It is sold alone or in combination with gentian violet and proflavine hemisulfate, and a prescription is not required. Due to its low cost and accessibility, patients may use brilliant green to self-treat dermatologic conditions. Green nails due to staining with brilliant green dye must be distinguished from other etiologies causing green nail discoloration, such as infection with Pseudomonas aeruginosa or Aspergillus, bullous disorders, jaundice, “old” hematomas, nail polish, and other exogenous pigments.