What is the small hard bump on right side of back head?

The most common cause of a small, hard bump on the right side of the back of the head is a sebaceous cyst. Sebaceous cysts are non-cancerous growths that form when sebum, an oil that is produced by the sebaceous glands, becomes trapped beneath the skin. Sebaceous cysts can occur anywhere on the body, but they are most common on the scalp, face, neck, and back.

Other possible causes of a small, hard bump on the right side of the back of the head include:

* Lipoma: Lipomas are non-cancerous growths that are made up of fat cells. Lipomas can occur anywhere on the body, but they are most common on the neck, back, and shoulders.

* Dermoid cyst: Dermoid cysts are benign growths that are made up of tissue that is normally found on the inside of the body, such as skin, hair, and teeth. Dermoid cysts can occur anywhere on the body, but they are most common on the face, neck, and back.

* Hemangioma: Hemangiomas are benign growths that are made up of blood vessels. Hemangiomas can occur anywhere on the body, but they are most common on the face, neck, and scalp.

* Meningioma: Meningiomas are rare tumors that arise from the meninges, the protective membranes that surround the brain and spinal cord. Meningiomas can occur anywhere along the spine, but they are most common in the thoracic (upper back) and cervical (neck) regions.

If you are concerned about a small, hard bump on the right side of the back of your head, it is important to see a doctor to rule out any serious medical conditions.