1.3 Papule

Papule

Focal, elevated, solid, circumscribed, palpable increase in substance of skin, sharp borders, surface usually smooth
Colors: if caused by inflammation,  red; if secondary to other deposits: red, brown or yellow
Size: ≤ 1 cm

May appear on entire body, for example maculo-papular exanthem.

Papules may coalesce to form plaque
Papule may enlarge to form nodule
May develop scales, crusts or erosion
May be associated with: macule (maculo-papular), vesicle (papulo-vesicular) or pustule (papulo-pustular)

Distinguish from nodule which is >0.5 cm
Inflammatory papules often pruritic

Multiple lesions: Drug exanthema, lichen planus, scabies, syphilis, acne
Single lesions: Melanocytic nevus, tumors such as early nodular basal cell carcinoma

Inflammatory infiltrate, deposits of lipids, proliferations of cells.