keratoacanthoma

A rapidly growing tumor that may be umbilicated, and usually occurs on exposed areas of the skin in elderly white men, which invades the dermis but remains localized and usually resolves spontaneously if untreated; microscopically, the nodule is composed of well-differentiated squamous epithelium with a central keratin mass that opens on the skin surface. [kerato- + G. akantha, thorn, +-oma, tumor]

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ker·a·to·ac·an·tho·ma .ker-ət-ō-.ak-.an-'thō-mə n, pl -mas also -ma·ta -mət-ə a rapidly growing skin tumor that occurs esp. in elderly individuals, resembles a carcinoma of squamous epithelial cells but does not spread, and tends to heal spontaneously with some scarring if left untreated

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n.

a firm nodule that appears singly on the skin, grows to 1-2 cm across in about six weeks, and usually disappears gradually during the next few months. Men are affected more often than women, commonly between the ages of 50 and 70. Keratoacanthomas occur mainly on the face; the cause is not known. Spontaneous healing may leave an unsightly scar; therefore treatment by curettage and cautery, or excision, may be required.

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ker·a·to·ac·an·tho·ma (ker″ə-to-ak″an-thoґmə) [kerato- + acanthoma] a locally destructive epithelial tumor with a superficial crater containing a keratin plug; it closely resembles squamous cell carcinoma clinically and histologically, but is benign and generally undergoes spontaneous regression. Exposure to sunlight is believed to play a role in its etiology.