A hard bump on the neck of the foot, if it protrudes from the surface of the skin, is usually an epidermal wart, which is caused by the proliferation of some epidermal fibrous tissue and is benign. If it’s a nuisance or if it often interferes with wearing shoes, it can be surgically removed. If it grows in the soft tissue under the skin, it may be a fibroma, cyst or sebaceous adenoma, among which sebaceous adenoma is also called powder tumor, which is caused by some inflammation due to the blockage of the skin glands and grows into a tumor with powder-like inflammatory tissue inside the envelope over time.