Should I be worried about this dark spot on my nail?

Dark spots on nails are a common concern in the office. Patients often are concerned about fungus or melanoma. However, brown spots are most commonly from trauma to the nail.  How can we know for sure?  Let’s learn today.

Dark spots on the nail can often be caused by a few things.  The three most common are blood, fungus and melanoma.  

Trauma to the nail bed can lead to an accumulation of blood under the nail.  Over time the blood usually turns brown leading to a well defined brown or burgundy “blob” under the nail.   Because the great toenail takes 12 months to grow out, it can take 12 months or more for the brown blob to move from the base of the nail out to the tip.  A brown spot that is progressing in this way and not enlarging at all is probably fine.  Often Dr Rosenberger can look at it closely to see the blood under the dermatoscope for confirmation.

Fungus under and in the nail plate often leads to a less distinct yellow, white, brown discoloration that does not grow out as the nail grows out.  The discoloration may progress down toward the cuticle more over time.  Patients with fungus under the nail often have fungus on their feet as well.  To definitively diagnose fungus, Dr Rosenberger does a clipping of the nail and sends it to the laboratory.  There are prescription topical and oral medications to treat fungus.  

Melanoma of course is the most worrying concern.  Most often melanoma starts as a brown streak in the nail that enlarges.  The brown discoloration often involves the cuticle or nail fold as well, called Hutchinson’s sign. To diagnose melanoma, a biopsy of the nail bed and/or cuticle is required.  This can lead to permanently deforming the nail.  To make it more difficult, there are a number of types of non-cancerous brown streaks in the nail. For this reason, we often follow, and ask the patient to follow, brown streaks in the nail with photography.  Rapid change or Hutchinson’s sign necessitate biopsy. 

To make things very, very difficult, some patients have more than one of these things.  One study showed that a large number of patients with melanoma in the nail remembered having trauma to their nail.  I am often reminded of a patient I treated in residency. He was a professional gardener and had trauma to his nail.  He ended up having trauma, fungus AND melanoma under his nail. He lost the entire end of his finger, but survived.  I try to remember that lesson when treating patients.  Every patient teaches me something! Thank you to you all!

If you have a concerning dark spot on your nail, make an appointment with a dermatologist to have it evaluated. 

If you know someone who may find this article helpful, please share it with them! Follow us on social media this week, and subscribe to our growing YouTube channel! If you would like to receive these posts in your email inbox, Subscribe to our Site.