This is a benign skin growth with an oily, waxy appearance, resembling a wart, which can be brown-toned or black in colour, and increases in frequency with age. Seborrheic keratoses are the most common benign tumour seen in humans. Commonly known as an ‘oil wart’ or ‘age wart’, they're unrelated to warts or HPV. They're sometimes mistaken for a ‘mole’, but aren't a true, cell-based mole. They originate from cells called keratinocytes in the upper layer of the skin.
When they first appear, they aren't raised from the skin's surface. They're usually a dirty yellow or light brown colour. Over time, the surface can become flaky. The oily crust on the surface can lift off, but the lesion thickens again. It can take on a rough, wart-like or cauliflower-like appearance. Sometimes it turns dark brown or black in colour, at which point it can be more easily confused with a mole.
It commonly settles on the face, scalp, back and front of the trunk. Beyond its appearance, it doesn't cause any physical complaint. Irritation, itching and bleeding can sometimes be seen. It doesn't develop into a malignant growth. Treatment can involve methods such as cryotherapy, curettage, cauterisation or laser.