A head bump may be due to an injury from a fall or accident, or it can develop as a symptom of medical conditions that can affect the scalp, such as folliculitis, sebaceous cysts and ringworm. The bump can develop gradually over time and be painless as in the case of a sebaceous cyst. However, a symptom of folliculitis is red, pimple-like bumps that may be filled with pus, explains WebMD.
Ringworm, or tinea capitis, is a fungal infection that may affect the scalp. Some symptoms of this condition are bald spots, a scaling area that is red and the formation of raised lesions called kerions that are filled with pus, notes the National Institutes of Health's MedlinePlus. In some patients, ringworm can also cause symptoms such as fever or inflamed lymph nodes.
Folliculitis develops when hair follicles become inflamed due to follicle damage, according to WebMD. This may lead to an infection that causes red pimples with pus to form on the scalp or other areas of the body where there are hair follicles.
Although a sebaceous or epidermoid cyst can form in the genital area, face or neck, it can also develop on the scalp. An epidermoid cyst is a bump that can range in color from tan to yellow and contains pus, states Healthline. If the cyst becomes infected, it can lead to symptoms that include pain and inflammation. In this case, doctors can prescribe antibiotics, drain the cyst or excise it.