Connective tissue nevi (CTN) are hamartomas that consist of excessive production of normal tissue, such as collagen (collagenomas), elastin (elastomas), or both, glycosaminoglycans (nevus mucinosis), and fibroblasts (fibroblastic CTN). CTN may be present at birth or arise during childhood and can be found anywhere on the body. They are usually hereditary but may be acquired.

CTN may be isolated or occur as part of a syndrome, such as tuberous sclerosis (collagenomas known as shagreen patches and fibrous forehead plaque), familial cutaneous collagenomas, Proteus syndrome (cerebriform connective tissue nevus), and Buschke-Ollendorff syndrome (elastomas known as dermatofibrosis lenticularis disseminata). Acquired collagenoma (athlete's nodules) may occur at sites of sporting injuries, such as the feet, knuckles, or knees.

CTN have a variable clinical appearance. They may appear as skin-colored, light brown, or yellowish papules or plaques with a smooth, cobblestone, or peau d'orange surface.