I do agree with you that this black spot on the skin of your back needs to be checked out, as do any new skin findings. You are right to worry about cancer, and this is the thing that your doctor
will be able to rule out for you. In particular, melanoma is a serious form of skin cancer, and it often looks like a mole or a 'black spot' on the skin. You should go see either a dermatologist
or your primary care doctor
for help with this problem.
Your doctor will evaluate the black spot, looking for worrisome signs that might suggest a cancer. These worrisome signs in particular include:
- any evidence that the spot is asymmetric (one half looking different than the other half)
- any evidence of an irregular, jagged border
- any changes in color in the spot (for example a darker spot inside the overall spot, or multiple colors in the same spot)
- size of the spot that is larger than the size of a pencil eraser
- any 'bumpiness' or change in the texture of the spot.
Based on what they find, if the doctor is worried about cancer, they will recommend a biopsy of the spot to rule this out.