Differential Diagnosis for a Bump on the Feet
Single Most Likely Diagnosis
- Plantar wart: A common and benign growth caused by the human papillomavirus (HPV), often appearing as a small, rough bump on the sole of the foot. The location and description of the bump, along with the prevalence of plantar warts, make this a likely initial consideration.
Other Likely Diagnoses
- Corns or calluses: Thickened areas of skin that can develop in response to repeated pressure or friction, often appearing as bumps. These are common on the feet, especially in areas subjected to pressure from poorly fitting shoes.
- Ingrown toenail: A condition where the nail grows into the surrounding skin, potentially causing a bump, redness, and pain. This is a frequent issue, especially if toenails are not trimmed properly.
- Bunion: A bony bump that forms on the joint at the base of the big toe, caused by the toe leaning towards the second toe. This can be painful and is often associated with poorly fitting shoes.
Do Not Miss Diagnoses
- Melanoma: Although rare, a bump on the foot could potentially be a sign of melanoma, especially if it is a new or changing mole. Given the potentially deadly nature of melanoma if left untreated, it's crucial to consider this diagnosis, even if it seems unlikely.
- Kaposi's sarcoma: A type of cancer that can cause lesions on the skin, including the feet. This is particularly relevant in immunocompromised patients.
- Infection (e.g., abscess, cellulitis): Bacterial infections can cause bumps, redness, and swelling. Identifying and treating infections promptly is essential to prevent serious complications.
Rare Diagnoses
- Gout: A form of arthritis characterized by sudden, severe attacks of pain, swelling, redness, and tenderness, often occurring at the base of the big toe. While not typically described as a "bump," gout can cause swelling that might be perceived as such.
- Neurofibroma: A benign nerve sheath tumor that can cause a bump under the skin. These are less common and might be considered if other diagnoses are ruled out.
- Foreign body reaction: A bump could potentially form as a reaction to a foreign object (like a splinter) under the skin. This would be less common on the feet unless there's a history of trauma.