Differential Diagnosis for a Hard Lump on the Back of the Head
Single Most Likely Diagnosis
- Subcutaneous hematoma or bruise: This is a common condition that can occur without a recalled injury, especially if the patient has a tendency to bruise easily or has a coagulation disorder. The fact that it's painful to touch and throbs at times is consistent with this diagnosis.
Other Likely Diagnoses
- Folliculitis or infected sebaceous cyst: These conditions can cause a painful lump on the scalp, especially if the patient has a history of acne or skin infections.
- Epidermoid cyst: A benign cyst that can cause a hard lump on the scalp, which may become inflamed and painful if infected.
- Lipoma: A benign fatty tumor that can cause a hard lump on the scalp, although it's usually painless.
Do Not Miss Diagnoses
- Meningioma or other brain tumor: Although rare, a brain tumor can cause a hard lump on the scalp if it erodes through the skull. This would be a serious and potentially life-threatening condition if missed.
- Osteomyelitis or skull infection: An infection of the bone or skull can cause a painful lump on the scalp, which can be serious if left untreated.
- Arteriovenous malformation (AVM): A rare condition where there's an abnormal connection between arteries and veins, which can cause a painful lump on the scalp if it ruptures.
Rare Diagnoses
- Dermatofibrosarcoma protuberans: A rare type of skin cancer that can cause a hard lump on the scalp.
- Metastatic tumor: A rare condition where a tumor from another part of the body metastasizes to the scalp, causing a hard lump.
- Eosinophilic granuloma: A rare condition that can cause a hard lump on the scalp, usually associated with Langerhans cell histiocytosis.