Jean Skinner, a nail technician from Essex, has shared a photograph of a client’s nail on Facebook in order to raise awareness about the little-known symptoms of melanoma (skin cancer).

In the image, a thumbnail is visible, with a strong dark line running through the middle. Captioning the picture, Skinner writes: “I had a walk-in nail client a couple weeks ago, and she had a straight dark vertical stripe down her nail.”

As soon as the client sat down, she asked Skinner to paint her nails with a varnish dark enough to cover the stripe, believing it to be due to a lack of calcium or a blood blister.

Skinner, however, took one look at the nail and realised that things were far more serious.

“This is melanoma,” she writes. “I did not want to frighten my client, but I told her she needed to see her doctor immediately.

“She called me today to tell me that, yes, the dark stripe indicated a very aggressive melanoma, and that it has already spread to her lymph nodes.”

The important reason why this photo of a fingernail has gone viral