A small growth of flesh in the armpit. There are several common causes. The most common cause is sebaceous gland infection. The sebaceous gland normally secretes sweat, which is discharged through a small tube, and since it is connected to the outside world, bacteria from the outside world can easily get into the sebaceous gland, which can cause an infection of the sebaceous gland. After the sebaceous glands become infected, swelling occurs. The skin protrudes outwards and forms a small flesh-like condition. The second common cause is warts, which can be in a small fleshy state when they first grow out.