Differential Diagnosis for Perianal Firm Small Lesion

Single Most Likely Diagnosis

• Hemorrhoid: A common condition that can present as a firm, small, round lesion near the anal verge, especially if it's not increasing in size. Hemorrhoids are typically found within 2-3 cm of the anal verge.

Other Likely Diagnoses

• Anal Tag or Skin Tag: A small, benign growth that can appear as a firm, round lesion near the anal verge. These are often remnants of previous hemorrhoids or anal fissures.
• Perianal Abscess: Although typically painful and fluctuant, a small, firm abscess could present similarly, especially if it's not yet fully developed or is partially drained.
• Anal Papillae: These are small, benign growths found at the anal verge, which could be mistaken for a firm lesion.

Do Not Miss Diagnoses

• Squamous Cell Carcinoma or Other Anal Cancers: Although less common, any new lesion near the anal verge warrants consideration of malignancy, especially in high-risk populations (e.g., those with a history of HPV infection, immunosuppression, or previous radiation therapy).
• Melanoma: A rare but aggressive form of skin cancer that can present as a new, firm lesion near the anal verge.

Rare Diagnoses

• Leiomyoma: A rare, benign tumor of smooth muscle origin that can occur in the anal region, presenting as a firm, small lesion.
• Granuloma: Inflammatory lesions that can result from various causes, including infections or foreign body reactions, and might present as firm, small lesions near the anal verge.
• Kaposi's Sarcoma: A rare cancer that can cause lesions in the anal area, especially in immunocompromised patients, such as those with HIV/AIDS.