Introduction
Clinical features
Dermoscopic features
Differential diagnoses
Histological explanation
A supernumerary nipple is a minor malformation of mammary tissue resulting in an extra nipple and associated tissue. It is also known as an accessory nipple or an ectopic nipple.
A supernumerary nipple is present at birth. It often appears similar to a congenital organoid or melanocytic naevus. Most supernumerary nipples are much smaller than the normal areola and nipple. They may be solitary or multiple, arising on one or both nipple line(s). They may be pink or brown, and at least the central nipple is elevated off the skin surface. There may be a central dimple. Supernumerary nipples may develop prominent hair at puberty.
Accessory nipples are most commonly characterised by the occurrence of an outer network-like structure accompanied by the presence of a scar-like area [1]. Other recognised features are explained in the table below.
Dermoscopic feature |
Definition |
|
|---|---|---|
Peripheral network (network-like structures) |
A network of brownish, interconnected thin lines over a background of diffuse tan pigmentation, located at the periphery of the lesion |
|
Central network-like structures |
A network of brownish, interconnected thin lines over a background of diffuse tan pigmentation, located centrally in the lesion |
|
Central white scar-like area |
Central, sharply circumscribed, round to oval, white area within the centre of an otherwise regular, light-to-dark brown pigmented lesion |
|
Cleft-like appearance |
A small rim, dividing the tip into two symmetrical parts |
|
White cobblestone-like structures |
Closely aggregated, larger, angulated whitish globules resembling cobblestones |
|
Central round dimpling with a plug |
Central roundish dimple filled with a darker plug |
|
Fisheye-like structures (mimicking comedo-like openings) |
Small, darker (brownish or black) dots visible in the form of sharply circumscribed, usually round or oval structures, mimicking comedo-like openings |
|
The differential diagnosis of a supernumerary nipple includes:
The supernumerary nipple often resembles the normal nipple:
In a supernumerary nipple, the epidermis is usually papillomatous, and the normal structures seen in nipple skin are found in the dermis. These include smooth muscle, breast ductal structures, and breast lobules.
