Gynecomastia: This condition is characterized by the benign enlargement of breast tissue in males, which can sometimes present as a tender lump behind the areola. It's a common condition, especially during puberty or with certain medical conditions and medications.

Breast Cyst or Abscess: These can occur in men and present as tender lumps. Breast cysts are fluid-filled sacs, while abscesses are collections of pus that can form due to infection.
Lipoma: A benign tumor composed of fat tissue, which can occur anywhere in the body, including behind the areola, and may feel like a lump.
Fat Necrosis: This is a condition where the fatty tissue in the breast becomes damaged, leading to the formation of a lump. It can be tender and may mimic other conditions.

Breast Cancer: Although rare in men, breast cancer can present as a lump behind the areola. It's crucial to not miss this diagnosis due to its potential severity and the importance of early treatment.
Infection or Abscess of the Breast Tissue: Infections can lead to serious complications if not treated promptly, including the formation of an abscess that may require drainage.
Sarcoidosis: A condition that can cause lumps or nodules in various parts of the body, including the breast tissue. It's less common but important to consider due to its systemic implications.

Hamartoma: A benign growth that can occur in the breast tissue, composed of a mixture of tissues normally found in the breast. It's rare and usually presents as a lump.
Phyllodes Tumor: A rare type of breast tumor that can be benign, borderline, or malignant. It tends to grow quickly but rarely spreads outside the breast.
Ductal Papilloma: Typically presents with nipple discharge, but can occasionally cause a lump if it becomes large enough or if there's associated bleeding or infection.