A papule is a circumscribed, solid elevation of skin with no visible fluid, varying in area from a pinhead to 1 cm.[nb 1] Papules can be brown, purple, pink or red in color, and can cluster into a papularrash. They may open when scratched and become infected and crusty. Larger non-blisterform elevated lesions may be termed nodules.
Papules are sometimes associated with other features such as crusts or scales.
^With regard to the quote "... varying in size from a pinhead to 1cm," depending on which text is referenced, some authors state the cutoff between a papule and a plaque as 0.5cm, not 1cm, while others state an entirely different measurement. Therefore, for this article, the 1cm cutoff is used which is discussed in Andrews' Diseases of the Skin: Clinical Dermatology (see references), a work considered by some dermatologists as an authority on this subject matter. See Lack of Standardization for complete discussion.