<unk> s are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A<unk>  is associated with the dimple sign; by applying lateral pressure, there is a central depression of the<unk> . Although typical<unk> s cause little or no discomfort, itching and tenderness can occur.<unk> s can be found anywhere on the body, but most often they are found on the legs and arms. They occur most often in women; the male to female ratio is about 1:4. The age group in which they most commonly occur is 20 to 45 years. Some physicians and researchers believe<unk> s form as a reaction to previous injuries such as insect bites or thorn pricks. They are composed of disordered collagen laid down by fibroblasts.<unk> s are classed as benign skin lesions, meaning they are completely harmless, though they may be confused with a variety of subcutaneous tumours. Deep penetrating<unk> s may be difficult to distinguish, even histologically, from rare malignant fibrohistocytic tumours like<unk> rcoma protuberans.<unk> s typically have a positive buttonhole sign, or central dimpling in the center.
Dermatofibroma
Blue nevus
Acral fibrokeratoma
Melanoma
Trichoepithelioma
Angiokeratoma
Chondroid syringoma
Dermatofibrosarcoma protuberans