Melanoma is a type of skin cancer, caused by the pigment producing cell melanocyte becoming cancerous. This form of cancer spreads extremely quickly, and can spread across the whole body in a very short space of time.

1500 to 2000 people are affect annually in Japan. If the cancer spreads, 90% of the affected patients have a life expectancy of 5 years and less.

The cancer occurs most commonly in the feet, in particular the large big toe. Although an early discovery of the cancer would save the individual this extremely difficult. As the cancer begins at the root of the nail of the toe, it is very difficult to discover at an early stage.

The cause isn’t quite understood, however it thought to be caused by some form of external stimuli.

The big difference between melanoma, ridged nails and subungual bleeding is whether or not a black line appears.

As melanoma is a cancerous cell, if left alone it will multiply over time. Both height, width and surface area will keep growing.

On the other hand, subungual bleeding related dark spots caused by exercise such as marathon running, will move its location as the nail grows.

However, what is explained here is only based on what we know so far. There are many components of the disease which are not yet quite understood. If a dark line or spot appears on your nail, it is highly recommended to have it examined by a specialist.


  1. A thin dark line appearing on the nail
  2. The dark line become larger over time
  3. You lose strength in your body
  4. The whole nail becomes black