Causes of Green Discoloration

Green discoloration of the skin, mucosa, and nails can be due to a variety of causes. It can range from an innocuous resolving bruise to serious systemic disease. Regardless, it is important to distinguish the cause of this coloration in order to appropriately manage the condition and limit the potential for complication.

Greenish nail syndrome is a term commonly used for a condition that can develop in individuals who frequently immerse their hands in water or those who engage in activities that result in the accumulation of moisture under the fingernails. It is most often caused by the bacterium Pseudomonas aeruginosa and manifests as a transverse line of greenish pigmentation in the nail plate. It can be associated with other symptoms such as onycholysis, brittle nails, and a pronounced odor.

The etiology of this condition is unknown, although a number of risk factors have been reported including frequent exposure to water, occupational contact with chemicals, and diabetes mellitus. It is also known to occur in patients taking certain medications such as tetracyclines, macrolides, and quinolones.

A 35-year-old man presented with onycholysis of the middle to distal portion of his left thumb nail with dark-greenish pigmentation in the separated portion of the nail. The patient denied any history of trauma to the nail or other significant illness and stated that he has been affected by this condition for over a year. He has been working as an office worker and primarily bathes with water at home. A fungal and bacterial smear of the subungual scrapings from the nail plate showed yeast and bacilli and a culture from the caseous material under the nail grew Candida albicans.

The sensitivity test of the nail with nadifloxacin 0.3% solution and itraconazole led to a complete resolution of her nail discoloration with no recurrence at the two-month follow-up visit.

Localized greenish discoloration during the course of resolving a bruise can occur, resulting from the degrading of hemoglobin to form bilirubin and its breakdown products. In this phenomenon, the tissue color changes from deep purple to black and blue to yellow before finally revealing its greenish hue. This condition may be alarming to the patient but it is important to reassure them that the discoloration will resolve and will not have any associated sequelae.

Another condition that can lead to greenish discoloration of the skin and nails is copper toxicity. This can be due to either new copper plumbing or the deterioration of existing copper plumbing. The presence of copper in the body can be detected by measuring blood copper levels. If copper toxicity is the cause of discoloration, the affected individual should run all faucets in their home and toilets until the color clears. If the problem is limited to a few faucets, it is probably best to call the city or county water department for assistance in resolving the issue. A home water testing kit is available that can be used to determine if the discoloration is from the municipal supply or from a specific faucet in the house.