Differential Diagnosis for a Persistent "Goose Egg" on the Forehead

Single Most Likely Diagnosis

• Hematoma: A collection of blood outside of blood cells, which can occur due to trauma. The presence of a "goose egg" near a vein that doesn't go away suggests a possible hematoma that has not fully resolved. This could be due to continued bleeding or the body's slow process of absorbing the blood.

Other Likely Diagnoses

• Bruise (Contusion): Similar to a hematoma but typically smaller and more superficial. It's possible that the "goose egg" is a large bruise that is taking time to heal.
• Subcutaneous Lipoma or Cyst: Although less likely, a persistent lump could be a lipoma (a benign tumor composed of fat tissue) or a cyst, which might have been mistaken for a hematoma or bruise due to its location and appearance.
• Insect Bite Reaction: In some cases, an insect bite can cause a significant reaction leading to a lump that resembles a "goose egg." This could be due to an allergic reaction or infection.

Do Not Miss Diagnoses

• Arteriovenous Malformation (AVM): Although rare, an AVM near the surface of the skin could cause a persistent lump or swelling, especially if it involves a vein. This condition requires immediate medical attention due to the risk of rupture and severe bleeding.
• Skin Cancer: Certain types of skin cancer, like a basal cell carcinoma or squamous cell carcinoma, could present as a persistent lump. While less likely, given the description, it's crucial not to miss this diagnosis due to its potential for serious consequences if left untreated.
• Infection or Abscess: An infection of the skin or an abscess could cause a lump that doesn't go away. This could be related to the initial trauma or a separate incident and requires prompt treatment to prevent spread or more serious complications.

Rare Diagnoses

• Pseudolymphoma: A rare condition that can mimic lymphoma but is typically benign. It could present as a lump under the skin.
• Dermatofibroma: A benign skin growth that could be mistaken for a persistent "goose egg" due to its firm nature and potential to appear after minor injury.
• Histiocytoma: A rare, benign growth that could present as a lump on the skin, potentially mistaken for a hematoma or other conditions listed above.