What is an irregular-shaped slightly inflamed hard bump under the scalp that hurts when you touch it and itchy on occasion?

An irregular-shaped slightly inflamed hard bump under the scalp that hurts when you touch it and itchy on occasion could be a number of things, including:

* Sebaceous cyst: A sebaceous cyst is a noncancerous growth that develops when a sebaceous gland, which produces oil for the skin, becomes blocked. Sebaceous cysts are usually round or oval and can range in size from a few millimeters to several centimeters. They are typically located on the scalp, face, neck, and back. Sebaceous cysts are not usually painful, but they can become inflamed and tender if they become infected.

* Lipoma: A lipoma is a noncancerous growth of fat cells. Lipomas are usually soft and doughy to the touch, and they can range in size from a few millimeters to several centimeters. They are typically located on the arms, legs, trunk, and buttocks. Lipomas are not usually painful, but they can be uncomfortable if they grow large or press on nerves.

* Pilomatrixoma: A pilomatrixoma is a noncancerous growth of hair matrix cells. Pilomatrixomas are usually firm and round, and they can range in size from a few millimeters to several centimeters. They are typically located on the scalp, face, and neck. Pilomatrixomas are not usually painful, but they can become inflamed and tender if they become infected.

* Squamous cell carcinoma: Squamous cell carcinoma is a type of skin cancer that develops in the squamous cells, which are the thin, flat cells that make up the outermost layer of the skin. Squamous cell carcinomas are typically scaly and crusty, and they can range in color from pink to red to brown. They are typically located on the face, ears, neck, and hands. Squamous cell carcinomas can be painful, especially if they become infected.

If you have an irregular-shaped slightly inflamed hard bump under the scalp that hurts when you touch it and itchy on occasion, it is important to see a doctor to get a diagnosis. The doctor may order tests, such as a biopsy, to determine the cause of the bump. Treatment options will depend on the diagnosis.