A mole just appeared, is it skin cancer?

A mole just appeared on the joint of my thumb, there was nothing there before. I'm really paranoid, could this be skin cancer or something?

Its just a mole, relax. ..

Are you sure it's a mole and not a blood blister?

At any rate, a cancerous lesion on the end of your thumb is very unlikely (unless you handle lots of chemicals). If it is a strange shape (wonky looking), different colours all over, bumpy surface, and if it gets larger over the next week then show it to the doc.

There is something called: ABCDE's of melanoma. It basically helps you identify a cancerous skin lesion:

What To Look For:
-A Mole changing size, shape or color
-Unusual growth on the skin
-A color change on the skin
-A sore that won't heal

A -- Asymmetry
One half doesn't match the other half.

B -- Border
The edges are ragged, blotched, or blurred.

C -- Color
The pigmentation is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue add to the mottled appearance.

D -- Diameter
The width is greater than six millimeters (about the size of a pencil eraser). Any growth of a mole should be of concern.

E -- Elevation/Evolution
A mole that is of different elevations/contours or ANY mole that has changed (evolution) should be checked by a qualified dermatologist as soon as the change is detected