Differential Diagnosis
- Single most likely diagnosis
- Bicipital tendinitis: The patient's symptoms of pain localized to the proximal humerus and shoulder joint, along with pain reproduction on resistive supination of the forearm, are consistent with bicipital tendinitis. The biceps tendon is involved in supination of the forearm, and inflammation or irritation of this tendon can cause pain in the proximal humerus and shoulder joint.
- Other Likely diagnoses
- Rotator cuff tendinitis: The patient's symptoms could also be consistent with rotator cuff tendinitis, particularly if the pain is localized to the shoulder joint. The rotator cuff tendons can be irritated or inflamed with repetitive activities such as tennis.
- Shoulder impingement syndrome: This condition occurs when the rotator cuff tendons are compressed or "impinged" by the acromion, leading to pain and inflammation. The patient's symptoms and activity level are consistent with this diagnosis.
- Labral tear: A labral tear can cause pain in the shoulder joint, particularly with activities that involve rotation or overhead movement. The patient's tennis activity could have led to a labral tear.
- Do Not Miss diagnoses
- Fracture: Although less likely, a fracture of the proximal humerus or shoulder joint should not be missed. A fracture could occur with a fall or direct blow to the shoulder, and would require prompt medical attention.
- Septic arthritis: This is a serious infection of the joint that requires prompt medical attention. Although less likely, septic arthritis should be considered in the differential diagnosis, particularly if the patient has a fever, redness, or swelling of the joint.
- Axillary nerve injury: The axillary nerve can be injured with trauma or repetitive activities, leading to pain and weakness in the shoulder joint. This diagnosis should not be missed, as it can lead to long-term weakness and disability.
- Rare diagnoses
- Osteonecrosis: This is a rare condition that occurs when the blood supply to the bone is disrupted, leading to bone death. Osteonecrosis can cause pain in the shoulder joint, but is less likely in this patient.
- Rheumatologic disorders: Certain rheumatologic disorders, such as rheumatoid arthritis or lupus, can cause pain and inflammation in the shoulder joint. Although rare, these diagnoses should be considered in the differential diagnosis, particularly if the patient has a history of autoimmune disorders.