Papula

A papule (from Latin papula – pimple) is a primary cell-free superficial element of a rash that rises above the skin level. A papule has a dense or soft consistency and, unlike a spot, can be palpated clearly.

Papules are usually defined as elements up to 0.5 cm in diameter (up to 1 cm in some classifications). The papule often leaves no scar, but may leave temporary pigmentation during the process of reversal.

Etiology and pathophysiology

Tissue elevation can be caused by:

• Cellular infiltration: The accumulation of inflammatory cells in the dermis (e.g. in psoriasis or red squamous lichen planus).
• Tissue hypertrophy: Overgrowth of the epidermis (warts).
• Deposition of metabolic products: For example, xanthomas in lipid metabolism disorders.

Differential diagnostic aspects

Papules may merge to form larger elements – plaques. It is important to distinguish a papule from a vesicle (which contains fluid) and from a nodule (which is deeper and larger).