Keratosis seborrhoic (plaque type)

Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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Frequent, benign, plaque-like, in one or more cases occurring in one or more cases, and in case of a longer period of existence also verrucous, fibro-epithelial neoplasia, which occurs more frequently with increasing age and is a cosmetic problem in case of multiple occurrence. S.a. Keratosis seborrhoeic (overview).

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Initial manifestation: 40-60 years

Clinical features
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Sharply defined, usually multiple, less often solitary, disseminated, roundish to oval, up to several centimetres in size, soft or firm, raised, greyish-brown or even black, broadly seated plaques on the lower surface with a smooth or velvety rough surface. Horn plugs, can be visualized very well under the reflected light microscope.

Passing itching may be present.

In intertriginous areas seborrhoeic keratoses are found as smooth, flat, often skin-coloured plaques, sometimes weeping.

Clinically, the flat seborrhoeic keratoses include the differently pigmented verruca-plana-like SK (see below seborrhoeic warts, verruca-plana-like), which are mainly observed on the back of the hand.

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The diagnosis "seborrhoeic keratosis" is on the one hand a "simple" diagnosis for the experienced physician. However, the most important thing is its reliable differentiation from a malignant melanoma. This distinction cannot be made with the necessary certainty by a non-physician. In this respect, lay or remote diagnoses of any kind should only be considered "preliminary" and not reliable. In any case, they require a qualified examination by a proven expert.


Please ask your physician for a reliable diagnosis. This website is only meant as a reference.


Last updated on: 29.10.2020