A Case of Green Nail Syndrome Diagnosed in the Emergency Department

Green nail syndrome (GNS) is a rare diagnosis in which a patient presents with green-yellow, green-blue, or green-brown discoloration of a finger or toenail. It occurs due to a Pseudomonas aeruginosa infection of the nail. Pseudomonas aeruginosa produces pigments that can infuse into the underside of the nail plate, creating a color change. Here, we present the case of a 34-year-old female with a green-brown area of discoloration of her right middle finger in which the diagnosis of GNS was made. The patient used acrylic nails, which is a known risk factor. The characteristic clinical context and physical exam findings of green-yellow, green-blue, or green-brown nail discoloration are said to be sufficient to make a working diagnosis of GNS. The differential diagnosis of GNS includes a subungual hematoma, a subungual melanoma, and exogenous yellow pigment exposure. The history, physical examination, and response to treatment will help to clarify the differential. Ciprofloxacin is a commonly used empiric treatment. Laboratory testing of a nail clipping can be used in cases that do not respond to treatment. Cultures of nail clippings appear to be specific, but not sensitive, to the detection of P. aeruginosa. Our patient saw an immediate improvement within a week of treatment, with complete resolution in eight weeks. This is a typical timeframe. Knowledge of the syndrome can be helpful to reduce patient anxiety and guide effective therapy.