One of the most common causes of a lump on the head is trauma to the site of the lump, which causes the tissues to swell and potentially bruise within one or two days of the injury, explains Healthline. Head lumps can also occur in the form of benign lesions, such as cysts or vascular masses, or due to cancerous masses, notes Columbia University Department of Otolaryngology.
Even mild trauma to the head can result in brain injury, so one should always seek medical attention if there is any doubt as to whether a head injury is severe enough to warrant a doctor's or hospital visit, according to BrainLine.org. Signs of a concussion following head trauma include loss of consciousness, headache, vomiting, memory loss, seizures and confusion. In children under the age of 2, parents should take any swelling or behavior changes as indicators of a potential concussion and seek immediate medical care for the child. A sleep-like state or complete lack of responsiveness is a sign of a more serious medical emergency, called a coma.
A physician can perform a biopsy of a lump on the head not related to an injury to determine whether it is cancerous, states Columbia University Department of Otolaryngology. Other diagnostic tests useful for diagnosing head masses include MRI scans, CT scans and neurological evaluations.