Q. I have had a faint, brownish- black, vertical line on my left index fingernail for the past two years.
I have seen general practitioners and a specialist but have been unable to get a proper diagnosis.
I am very worried that it may be something serious. Can you help?
A. Pigmented nail lesions are challenging to evaluate and treat.
There can be a variety of causes, from simple injuries that cause a little bleeding under the nail, to more sinister causes like cancer.
The evaluation of a pigmented nail lesion begins with the doctor taking the patient's history, which includes age, hand dominance, injuries, medication intake, family history, as well as how long the lesion has been present and how it started, and whether it has evolved over time.
The nail examination entails an assessment of the width, number of bands (lines), its borders and interface with the surrounding nail complex.
To arrive at a definitive diagnosis may require removing the nail to inspect the underlying nail bed, and a biopsy. This procedure can cause permanent scarring and distortion of the nail.
Therefore, it is performed when the lesion is suspected to be malignant. The photograph you provided is suggestive of Melanonychia striata, a benign form of nail pigmentation.
Although most of these cases are benign, there is a remote possibility of underlying malignancy.
I recommend that you keep photographic records of your nail to monitor for changes to pigment pattern and follow up with the specialist that you have seen, so that he can perform a biopsy if there are any changes.
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Dr Anthony Foo
Consultant in the Hand & Reconstructive Microsurgery Centre at National University Hospital