Differential Diagnosis for a Small Bump on the Anus
Single Most Likely Diagnosis
- Hemorrhoid: This is the most common cause of a small bump on the anus, often resulting from increased pressure on the veins in the anal region, which can be due to constipation, straining during bowel movements, or prolonged sitting.
Other Likely Diagnoses
- Anal skin tag: A small, usually harmless growth that can appear on the outside of the anus, often as a result of a previous hemorrhoid or anal fissure.
- Anal wart: Caused by the human papillomavirus (HPV), these can appear as small bumps on the anus and are usually sexually transmitted.
- Anal fissure: A small tear in the lining of the anus, which can cause pain and bleeding, and may appear as a small bump or swelling.
Do Not Miss Diagnoses
- Anal cancer: Although rare, it's crucial to rule out cancer, especially if the bump is persistent, grows, or is accompanied by other symptoms like bleeding, pain, or changes in bowel habits.
- Squamous cell carcinoma or basal cell carcinoma: These types of skin cancers can occur in the anal region and may initially present as a small bump.
Rare Diagnoses
- Condyloma acuminatum (genital warts): While not exclusive to the anus, they can occur there and appear as small bumps.
- Molluscum contagiosum: A viral infection that causes small, pearly, or flesh-colored bumps, which can appear on the anus, though this is less common.
- Dermatological conditions like psoriasis, eczema, or lichen sclerosus: These can cause skin changes and bumps in the anal area, though they are less common causes of a single small bump.