Causes

The exact cause of cutaneous T-cell lymphoma isn't known.

In general, cancer begins when cells develop changes (mutations) in their DNA. A cell's DNA contains instructions that tell a cell what to do. The DNA mutations tell the cells to grow and multiply rapidly, creating many abnormal cells.

In cutaneous T-cell lymphoma, the mutations cause too many abnormal T cells that attack the skin. T cells are part of your immune system, and they normally help your body fight germs. Doctors don't know why the cells attack the skin.