This 82 year old man developed raised, painless, pigmented lesion that gradually enlarged over a couple of years and then stabilised. It has not bled, ulcerated or scabbed. The surrounding tissue is not distorted. There is no telangiectasis.
This lesion is a seborrheic keratosis. They are common, benign lesions that are most common in elderly caucasian individuals. The precise cause is not known but they are probably associated with long term sun exposure, but can also occur in body folds, probably from skin friction. Their name is misleading as they are formed from sebaceous glands and they do not only occur in a seborrheic distribution (scalp, mid-face, chest, upper back). Occasionally pigmented skin malignancies such as melanomas and pigmented squamous cell carcinomas can look like seborrheic keratosese. Therefore if they have any atypical features (e.g. vascularisation) or they continue to enlarge they should be referred to an ophthalmologist or dermatologist depending on their location for further assessment and consideration of a biopsy. Extremely rarely multiple, eruptive seborrheic keratoses are a sign of internal malignacy; this is called Leser-Trelat sign, and necessitates referral for full examination and bodily imaging.
Seborrheic keratoses can be removed if desired by the patient. They can be removed by surgery or a range of destructive measures such as cryotherapy and eletrocautery.