Differential Diagnosis

The patient presents with joint pain and stiffness affecting her hands, fingers, knees, and feet, which has been ongoing for 6 days. Given her symptoms and laboratory results, the following differential diagnoses can be considered:

• Single most likely diagnosis
  • Repetitive Strain Injury or Overuse Syndrome: This diagnosis is likely due to the patient's occupation, which involves frequent and repetitive use of her hands and arms. The symptoms of joint pain and stiffness, particularly after repetitive use, support this diagnosis.
• Other Likely diagnoses
  • Osteoarthritis: Although the patient is relatively young, osteoarthritis can occur in individuals with a history of repetitive joint stress or trauma. The lack of systemic symptoms and normal laboratory results make this diagnosis plausible.
  • Tendinitis or Bursitis: Inflammation of the tendons or bursae surrounding the joints could cause pain and stiffness, especially with repetitive use. The patient's occupation and symptoms suggest this possibility.
  • Regional Pain Syndrome: This condition, also known as repetitive strain injury, can cause pain and stiffness in the affected areas, particularly after repetitive use.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Septic Arthritis: Although the patient denies fever, chills, or recent illness, septic arthritis is a medical emergency that requires prompt diagnosis and treatment. The lack of visible joint swelling or redness does not rule out this diagnosis.
  • Lyme Arthritis: If the patient has been exposed to ticks or has a history of Lyme disease, Lyme arthritis could be a consideration, although the normal laboratory results make this less likely.
  • Crystal Arthropathy (e.g., Gout or Pseudogout): Although the uric acid level is normal, crystal arthropathy can still occur, and it is essential to consider this diagnosis, especially if the patient's symptoms worsen or do not respond to treatment.
• Rare diagnoses
  • Seronegative Spondyloarthropathy: Conditions like psoriatic arthritis, reactive arthritis, or enteropathic arthritis are less likely given the patient's normal laboratory results and lack of systemic symptoms.
  • Hematologic or Oncologic Conditions: Although rare, conditions like multiple myeloma or leukemia can cause joint pain and stiffness. However, the normal laboratory results, including CBC and CMP, make these diagnoses less likely.