A<unk>  is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some have crusts or scales. A<unk>  can be flesh colored, yellow, white, brown, red, blue or purplish. There may be just one or many, and they may occur irregularly in different parts of the body or appear in clusters. It does not contain fluid but may progress to a pustule or vesicle. A<unk>  is smaller than a nodule; it can be as tiny as a pinhead and is typically less than 1 cm in width, according to some sources, and 0.5 cm according to others. Its color might indicate its cause, such as white in milia, red in eczema, yellowish in xanthoma and black in melanoma. They may open when scratched and become infected and crusty.
Papule
Polyp 
Polypill
Nodule 
Dermatophyte
Epulis
Hair
Lesion