What is a café-au-lait macule?

Café-au-lait macules (CALMs) are uniformly light-brown (the color of coffee with cream) macules that vary in size from 2 to 20 cm and often have irregular borders. They are characterized by increased melanin in both melanocytes and keratinocytes and by giant melanosomes. CALMs grow proportionately to body growth and remain stable in size after body growth has completed. CALMs are found in 10% to 20% of the general population; however, multiple CALMs are relatively rare (0.25% to 0.5%) in the general population and should alert you to the possibility of an associated disease. Multiple CALMs are most commonly associated with neurofibromatosis (see Chapter 5), and large CALMs with the McCune-Albright syndrome (see Chapter 18).

Landau M, Krafchik BR: The diagnostic value of café-au-lait macules, J Am Acad Dermatol 40:877–890, 1999.