Papule

PAPULE (papula), nodule, a morphological element of many dermatoses—a small elevation on the surface of the skin or mucous membrane, from the size of a poppy seed to that of a large pea, firm and compact (distinct from a vesicle), having a limited existence and growth (distinct from a tumor) and disappearing spontaneously without a scar (distinct from a tubercle), either without a trace or with the temporary leaving of an erythematous, pigmented, or achromic spot. Papules can be of both an inflammatory nature (syphilitic, psoriatic, and others) and non-inflammatory (for example, flat warts of youth). The form of papules ranges from oval, round, or polygonal disk to cone, hemisphere. The color ranges from the color of normal skin to pink-red, brown, violet. Histologically, papules are formed either by hyperplasia of cells of various layers of the epidermis (epidermal papules), or by serous-cell infiltrate in the superficial layers of the skin (dermal papules), or by both of these processes (epidermo-dermal papules). Papules arise either immediately as such—primarily, or secondarily, for example, from an erythematous spot, or the deposition of infiltrate occurs under a vesicle, pustule, etc. Subsequently, depending on pathological changes in the epidermis and dermis, papules may flake on the surface, bear vesicles, pustules, crusts, erosions, etc. Larger papules, 'coin-shaped', 'in a silver ruble', 'palm-sized', etc. are called 'disks', 'plaques'; flat superficial infiltrates, spread over a wide area, are called papular infiltrates.