Lateral Epicondylitis: This is the most common cause of tennis elbow, characterized by inflammation of the tendons that attach to the lateral epicondyle of the humerus. It is often related to overuse or repetitive strain on the forearm extensors.

Medial Epicondylitis: Also known as golfer's elbow, this condition involves inflammation of the tendons that attach to the medial epicondyle, affecting the flexor muscles of the forearm. It presents with pain on the inner aspect of the elbow.
Radial Tunnel Syndrome: This condition involves compression of the radial nerve as it passes through the radial tunnel near the elbow, leading to pain and weakness in the forearm and wrist.
Elbow Bursitis: Inflammation of the bursae around the elbow can cause pain and swelling, often due to repetitive motion or direct trauma.

Fracture or Avulsion Injury: Although less common, a fracture or avulsion injury around the elbow can present with similar symptoms to tennis elbow and must be ruled out to avoid delayed diagnosis and treatment.
Infectious Arthritis: Bacterial or fungal infections of the elbow joint can cause severe pain, swelling, and decreased range of motion, requiring prompt diagnosis and treatment to prevent serious complications.
Neoplastic Processes: Tumors, either benign or malignant, can occur around the elbow and may mimic the symptoms of tennis elbow. Early detection is crucial for effective management.

Osteochondritis Dissecans: A condition where a piece of cartilage and bone in the joint becomes damaged, leading to pain and swelling. It is more common in younger individuals.
Entrapment Neuropathies: Besides radial tunnel syndrome, other nerves like the ulnar or median nerve can become entrapped, leading to specific patterns of pain, numbness, and weakness.
Referred Pain from Cervical Spine: In some cases, pain referred from the cervical spine can mimic tennis elbow, especially if there is involvement of the cervical roots that contribute to the brachial plexus.