Dermoid cyst: A common benign growth that can appear as a bump on the head, often present at birth or developing during childhood. It is usually harmless and may be removed surgically if necessary.

Epidermoid cyst: Similar to a dermoid cyst but containing only skin cells and keratin, often appearing as a firm, movable bump under the skin.
Lipoma: A benign tumor composed of fat tissue, which can appear as a soft, movable bump on the head.
Hematoma: A collection of blood outside of blood vessels, which can cause a bump on the head, often resulting from trauma or injury.
Abscess or boil: A localized infection that can cause a painful bump on the head, often accompanied by redness, swelling, and pus.

Meningioma: A rare, usually benign tumor arising from the membranes surrounding the brain and spinal cord, which can cause a bump on the head if it grows through the skull.
Osteoma: A benign bone tumor that can appear as a hard, fixed bump on the head, which may be associated with a genetic condition.
Rhabdomyosarcoma: A rare, malignant tumor of soft tissue that can appear as a bump on the head, often accompanied by other symptoms such as pain, swelling, and limited mobility.
Neuroblastoma: A rare, malignant tumor that can arise in the head or neck, often appearing as a bump or mass.

Ewing's sarcoma: A rare, malignant bone tumor that can appear as a bump on the head, often accompanied by systemic symptoms such as fever, weight loss, and fatigue.
Langerhans cell histiocytosis: A rare disorder characterized by an overproduction of immune cells, which can cause bumps or lesions on the head, often accompanied by other systemic symptoms.
Cephalohematoma: A rare condition characterized by bleeding between the skull and its outer covering, often appearing as a bump on the head, usually in newborns.