Differential Diagnosis for Medial Left Upper Arm Pain

The patient presents with pain on the medial side of the left upper arm, and an ultrasound scan shows focal relatively hypoechoic changes. Based on this information, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Medial Epicondylitis: This condition, also known as golfer's elbow, is characterized by pain and inflammation on the medial side of the elbow, which could radiate to the upper arm. The hypoechoic changes seen on the ultrasound could represent inflammation or tendon damage, making this a plausible diagnosis given the location and symptoms.

• Other Likely Diagnoses

  • Ulnar Nerve Entrapment: The ulnar nerve runs down the arm and through the medial epicondyle at the elbow. Entrapment or compression of this nerve can cause pain, numbness, and tingling in the arm and hand. The focal hypoechoic changes could potentially represent nerve swelling or adjacent soft tissue changes.
  • Medial Head of Triceps Tendinopathy: Although less common than lateral tendinopathies, the medial head of the triceps can also be affected by overuse or direct trauma, leading to pain and hypoechoic changes on ultrasound due to tendon inflammation or degeneration.
  • Brachialis Muscle Strain: The brachialis muscle is located in the upper arm and could potentially cause medial arm pain if strained. Hypoechoic changes on ultrasound might indicate muscle injury or inflammation.

• Do Not Miss Diagnoses

  • Acute Ulnar Nerve Neuroma or Tumor: Although rare, a neuroma or tumor affecting the ulnar nerve could present with similar symptoms and must be considered to avoid missing a potentially serious condition.
  • Infectious Process (Abscess or Cellulitis): An infectious process in the soft tissues of the arm could cause pain and hypoechoic changes on ultrasound. This would be a medical emergency requiring prompt treatment.
  • Vascular Injury or Thrombosis: Injury to the blood vessels of the arm, such as the brachial artery or its branches, could lead to significant complications, including limb ischemia. This must be considered, especially if there's a history of trauma.

• Rare Diagnoses

  • Lipoma or Soft Tissue Tumor: A benign or malignant tumor in the soft tissues of the arm could cause focal hypoechoic changes on ultrasound. While rare, these should be considered in the differential diagnosis, especially if the lesion has atypical features or if symptoms persist despite conservative management.
  • Parosteal Lipoma: A rare condition where a lipoma forms adjacent to bone, potentially causing pain and hypoechoic changes on imaging if it compresses nearby structures.
  • Nerve Sheath Tumor: Benign tumors arising from the nerve sheath, such as neurofibromas or schwannomas, could cause symptoms similar to ulnar nerve entrapment and must be considered in the differential diagnosis.