Differential Diagnosis
- Single most likely diagnosis:
- Myofascial pain syndrome: The patient's symptoms of a "weird discomfort" in the left latissimus dorsi region, especially with pressure or friction, and the presence of a knot/nodule that moves with the muscle, are consistent with myofascial pain syndrome. The patient's occupation as an Uber Eats delivery person, which involves frequent driving and potentially repetitive strain on the left arm, supports this diagnosis.
- Other Likely diagnoses:
- Latissimus dorsi strain: The patient's symptoms of pain and discomfort in the left latissimus dorsi region, particularly with pressure or friction, could be indicative of a strain in this muscle.
- Thoracic outlet syndrome: The patient's symptoms of pain and discomfort in the left latissimus dorsi region, as well as the need to use a pillow to reduce discomfort when sleeping on the left side, could be suggestive of thoracic outlet syndrome.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Pancoast tumor: Although unlikely, a Pancoast tumor (a type of lung cancer that affects the apex of the lung) could cause pain and discomfort in the shoulder and arm region, including the latissimus dorsi muscle. It is essential to consider this diagnosis due to its potential severity and impact on patient outcomes.
- Brachial plexus injury: A brachial plexus injury could cause pain, numbness, and weakness in the arm and shoulder region, including the latissimus dorsi muscle. This diagnosis should not be missed due to its potential for long-term disability.
- Rare diagnoses:
- Fibromatosis: A rare condition characterized by the growth of fibrous tissue, which could cause a palpable mass and pain in the affected area.
- Desmoid tumor: A rare type of tumor that can occur in the muscle or soft tissue, which could cause pain and discomfort in the affected area.