What causes café au lait birthmarks?

What causes café au lait birthmarks?

What causes café-au-lait spots? An increase in the number of skin cells (melanocytes) that produce the protective pigment that darkens skin (melanin) in the thin outer layer of your skin (epidermis) causes café-au-lait (CAL) spots. The reason for the increase in melanocyte cells is unknown. In most cases, café au lait spots are harmless and normal. Having more than six café au lait spots at one time, however, may be a sign of neurofibromatosis type 1 (NF1), an underlying genetic condition.I find that six or more café-au-lait spots are usually visible by around 2 years of age, and new spots do not usually appear after that time, though spots tend to tan upon sun exposure, so may become more distinct with time.