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A seborrheic keratosis (also known as "seborrheic verruca," and "senile wart"〔Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.〕) is a benign skin growth that originates in keratinocytes. Like liver spots, seborrheic keratoses are seen more often as people age.〔(Moles, Freckles, Skin Tags, Benign Lentigines, and Seborrheic Keratoses ) from the Cleveland Clinic website〕 The lesions appear in various colors, from light tan to black. They are round or oval, feel flat or slightly elevated (like the scab from a healing wound), and range in size from very small to more than across.〔(Seborrheic keratosis: Symptoms ), from the Mayo Clinic website〕 They can resemble warts,〔 though they have no viral origins. They can also resemble melanoma skin cancer, though they are unrelated to melanoma. Because only the top layers of the epidermis are involved, seborrheic keratoses are often described as having a "pasted on" appearance. Some dermatologists refer to seborrheic keratoses as "seborrheic warts"; these lesions, however, are usually not associated with HPV, and therefore such nomenclature is discouraged. ==Classification== Seborrheic keratoses may be divided into the following types:〔 * Common seborrheic keratosis (basal cell papilloma, solid seborrheic keratosis) * Reticulated seborrheic keratosis (adenoid seborrheic keratosis) * Stucco keratosis (digitate seborrheic keratosis, hyperkeratotic seborrheic keratosis, serrated seborrheic keratosis, verrucous seborrheic keratosis) -- Often are light brown to off-white. Pinpoint to a few millimeters in size. Often found on the distal tibia, ankle, and foot. * Clonal seborrheic keratosis * Irritated seborrheic keratosis (basosquamous cell acanthoma, inflamed seborrheic keratosis) * Seborrheic keratosis with squamous atypia * Melanoacanthoma (pigmented seborrheic keratosis) * Dermatosis papulosa nigra—Commonly found among adult dark-skinned individuals, presents on the face as small benign papules from a pinpoint to a few millimeters in size. * Inverted follicular keratosis Also see: * The sign of Leser-Trélat 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Seborrheic keratosis」の詳細全文を読む スポンサード リンク
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