Going green: The complexities of the green nail syndrome
By Warren R. Heymann, MD
February 3, 2021
Vol. 3, No. 5
GNS has been described as a triad of green discoloration of the nail plate, proximal paronychia, and distal onycholysis. The color of the nail may vary from blue-green, to green-brown, or green-yellow. Usually only one or two nails are involved. GNS often is noted in patients with other nail disorders such as psoriasis or paronychia, especially in the context of a moist environment; this is particularly true for hairdressers, dishwashers, and medical personnel. The differential diagnosis includes oncychomycosis, subungal hematoma, or melanoma. (1)
Overwhelmingly, Pseudomonas aeruginosa (a Gram-negative, aerobic coccobacillus) is the responsible bacterium causing GNS by producing pyoverdin and pyocyanin. (2) There is a fascinating reciprocal relationship between P. aeruginosa and fungi or yeast. P. aeruginosa has antifungal activity because of its production of pyocyanin and 1‐hydroxyphenazine. Additionally, it has been demonstrated that P. aeruginosa forms a dense biofilm on C. albicans filaments thereby killing the yeast. (3) The bacterium has been shown to inhibit the growth of Trichophyton rubrum and T. mentagrophytes. (4) Alternatively, dermatophytosis predisposes to infections by P. aeruginosa; it has been isolated from 7% of all clinically suspected cases of onychomycosis, and from 14% of mycologically confirmed onychomycosis cases using calcofluor/KOH. (5) Onychomycotic nails may provide an environment suitable for prolonged carriage of P. aeruginosa because nail spaces created beneath the lateral folds are ideal for their growth. (3)
Surprisingly, there have been remarkably few studies defining the relationship of GNS with onychomycosis. Ohn et al performed a retrospective study of 23 cases of GNS in which clippings utilizing PAS or GMS stains were performed. Five patients (21.7%) had immunosuppressive conditions including internal malignancies, autoimmune disorders, and diabetes mellitus. A previous history of nail diseases was reported in 13 cases (56.5%), including 12 patients with a history of onychomycosis and 1 patient with nail psoriasis. Of affected nails, 18 (78.3%) were toenails and 5 (21.7%) were fingernails. Involvement of the great toenail or thumbnail was found in 22 patients (95.7%). Fungal coinfection was noted in 15 patients (65.2%). The authors concluded that onychomycosis was frequently associated with GNS and might be a predisposing factor of GNS. They recommended that the nails in patients with GNS be carefully examined to detect possible fungal infections. (6)
Treatment begins with measures to keep the nails dry, avoiding wet work if possible. Briefly soaking the nail in a diluted sodium hypochlorite (bleach) solution also helps to suppress bacterial growth. (7) I often recommend diluted acetic acid (vinegar) soaks. Additionally, either topical or systemic antibiotics may be utilized. Bae et al report the successful treatment of GNS with tobramycin eye drops. (8) Fluoroquinolones such as ciprofloxacin or levofloxacin are regarded as first-line systemic treatment. (As per Epocrates, do not forget to inform patients of the black box warning regarding tendinitis/tendon rupture, peripheral neuropathy, and CNS effects that may occur during treatment or months after discontinuation of the drug!) Nail extraction may be required in refractory cases.
I started to turn green after thinking about how I may not have been managing GNS optimally. While straightforward, the disorder has levels of complexity that demand our attention. Whether it is diagnosing attendant onychomycosis or properly warning our patients of the risk of fluoroquinolones, there is much more to GNS than eradicating its color.
Point to Remember: The green nail syndrome requires a careful assessment to rule out and treat associated disorders (especially onychomycosis) in addition to eradicating Pseudomonas aeruginosa infection.
Our Expert’s Viewpoint
Richard K. Scher, MD
Clinical Professor of Dermatology
Weill Cornell Medicine/Dermatology
When I think of green, I think of St Patrick's Day, spring, and the green nail syndrome. An often overlooked onychodystrophy, frequently referred to as chloronychia or Goldman-Fox syndrome, with its bright green color, presents a plethora of pitfalls for the physician. The spectrum is wide from nail melanoma to infections like Pseudomonas, onychomycosis, and Candidiasis to troublesome subungual hematomas.
It behooves us to be alert to the fact that several complications may occur. The green nail with onycholysis and paronychia may be masking a melanoma that mandates a biopsy. The occurrence of Pseudomonas aeruginosa seduces the presence of fungal nail infections such as Trichophyton rubrum. As times one may accompany the other as a result of subungual nail unit spaces.
After correct diagnoses have been established — preceded by necessary studies — then a range of therapies are available which include avoidance of moisture, topical acetic acid/hypochlorite soaks, antibiotics, and others. Finally, health care workers and the elderly are prone. Don’t go red, go green.
Dr. Scher had disclosed financial relationships with the following to the AAD at the time of publication: MOE Medical Devices LLC. Full disclosure information is available at coi.aad.org.
Schwartz RA, Reynoso-Vasquez N, Kapila R. Chloronychia: The Goldman-Fox syndrome – implications for patients and healthcare workers. Indian J Dermatol 2020; 65: 1-4.
Chiriac A, Brzezinski P, Foia L, Marincu L. Chloronychia: Green nail syndrome caused by Pseudomonas aeruginosa in elderly persons. Clin Interv Aging 2015; 10: 265-267.
Yang YS, Ahn JJ, Shin MK, Lee MH. Fusarium solani onychomycosis of the thumbnail coinfected with Psuedomonas aeruginosa: Report of two cases. Mycoses 2011; 54: 168-171
Treat J, James WD, Nachamkin I, Seykora J. Growth inhibition of Trichophyton species by Pseudomonas aeruginosa. Arch Dermatol 2007; 143: 61-64.
Thomas LM, Elewski B. The presence of Pseudomonas aeruginosa in clinically suspected dermatophyte onychomycosis. J Am Acad Dermatol 2004; 50S: 90.
Ohn J, Yu DA, Park H, Cho S, Mun JH. Green nail syndrome: Analysis of the association with onychomycosis. J Am Acad Dermatol 2020; Jan 28 [Epub ahead of print].
Gish D, Romero BJ. Green fingernail. J Fam Pract 2017; 66: e7-e9.
Bae Y, Lee GM, Sim JH, Lee S, et al. Green nail syndrome treated with the application of tobramycin eye drop. Ann Dermatol 2014 Aug; 26(4): 514–516.
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