Green fingernail

Medication-induced effects. Minocycline may cause bluish nail discoloration similar to that produced by infection with P aeruginosa, but it is rare for only a single nail to be involved. In addition, pigmentation changes are often present elsewhere on the body, including the sclerae, teeth, and pinna.

Another medication known to color the nails blue is colloidal silver, which is still sold as a dietary supplement or homeopathic remedy to treat a wide range of ailments.⁶ (Of note: In 1999, the Food and Drug Administration issued a final rule saying that colloidal silver isn’t safe or effective for treating any disease or condition.¹²)

Glomus tumor. Another cause of blue nails is glomus tumors, relatively uncommon perivascular neoplasms that are typically found in the subungual region. These tumors are generally accompanied by localized tenderness, cold sensitivity, and paroxysms of excruciating pain that are disproportional to the size of the tumor.

Briefly soaking the nail in a bleach solution helps to suppress bacterial growth.

Imaging studies may aid in the diagnosis, in addition to pathologic confirmation. Magnetic resonance imaging is the most sensitive imaging modality; if a glomus tumor is present, it most often appears as a well-circumscribed T2 hyperintense lesion.¹³

Exogenous pigmentation. Nails may become discolored due to exposure to various toxins or chemicals. Frequent culprits include eosin, methylene blue, henna, hair dye, and tobacco.⁹

Antibiotics and measures to keep the nail dry will help resolve infection

When chronic nail wetness is a contributing factor, treatment begins with measures to keep the nails dry. In addition, either topical or systemic antibiotics may be used to eradicate the infection. Topical applications with agents such as nadifloxacin have been shown to be effective in several case reports,³ but large-scale controlled trials are lacking. Fluoroquinolones are regarded as first-line systemic treatment.⁵ Briefly soaking the nail in a diluted sodium hypochlorite (bleach) solution also helps to suppress bacterial growth. Nail extraction may be required in refractory cases.

For our patient, we prescribed ciprofloxacin 500 mg twice a day for 10 days, plus bleach soaks (one part bleach to 4 parts water) twice a day. We recommended that our patient wear gloves for household tasks that involved immersing her hands in water, and drying her finger with a hair dryer after bathing.

CORRESPONDENCE
David Gish, MD, University of Virginia Health System, 1215 Lee St. Charlottesville, VA 22908; dsg5n@hscmail.mcc.virginia.edu.