Olecranon Bursitis: This condition is characterized by inflammation of the bursa at the elbow, leading to a cyst-like swelling. It's a common issue, especially in individuals who frequently lean on their elbows or have experienced trauma to the area.

Ganglion Cyst: A common benign lump that can occur on the elbow, resulting from a herniation of a joint capsule or tendon sheath. It's more frequently seen on the wrist but can occur on the elbow.
Epidermoid Cyst: A benign cyst that can appear anywhere on the skin, including the elbow, often resulting from a blocked oil gland or hair follicle.
Sebaceous Cyst: Similar to an epidermoid cyst, it's a benign, usually harmless cyst that can appear on the elbow, originating from the oil glands in the skin.

Infected Bursitis: While olecranon bursitis is the most likely diagnosis, an infected bursa is a serious condition that requires prompt antibiotic treatment. Failure to diagnose and treat can lead to severe infection and potential long-term damage.
Tuberculous Bursitis: A rare form of bursitis caused by tuberculosis infection. Although uncommon, missing this diagnosis could have significant health implications due to the need for specific antitubercular therapy.
Malignant Tumor: Although rare, a cyst on the elbow could potentially be a sign of a malignant tumor, such as a soft tissue sarcoma. Early detection is crucial for effective treatment.

Synovial Cyst: A rare condition where a cyst forms in the synovial membrane of the joint, which can occur at the elbow.
Hygroma: A rare, benign cystic lesion that can occur at the elbow, often associated with trauma or overuse.
Cystic Hygroma of the Elbow: An extremely rare condition, usually presenting in infancy or early childhood, characterized by a fluid-filled sac (cyst) that most commonly occurs in the head or neck but can rarely be found at the elbow.