Differential Diagnosis for Morning Neck Stiffness and Multiple Joints Pain

Given the symptoms of morning neck stiffness and multiple joints pain for more than 2 weeks, with a negative dsDNA (double-stranded DNA) test, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis
  • Rheumatoid Arthritis (RA): Although the negative dsDNA test might lean away from systemic lupus erythematosus (SLE), RA is a common cause of multiple joint pains and morning stiffness. The absence of dsDNA antibodies does not rule out RA, as these antibodies are more specific to SLE.
• Other Likely Diagnoses
  • Osteoarthritis (OA): Especially if the neck stiffness is prominent, OA could be a consideration, particularly in older adults. However, OA typically affects weight-bearing joints and those with previous injuries or overuse.
  • Psoriatic Arthritis (PsA): This condition can cause joint pain and stiffness, often accompanied by skin psoriasis. The absence of dsDNA does not affect the likelihood of PsA.
  • Ankylosing Spondylitis (AS): A form of arthritis that primarily affects the spine, although other joints can be involved. Morning stiffness and improvement with activity are characteristic.
• Do Not Miss Diagnoses
  • Infectious Arthritis: Such as septic arthritis, which is a medical emergency. The presence of fever, significant joint swelling, or systemic symptoms would increase suspicion.
  • Lyme Arthritis: Caused by Borrelia burgdorferi, transmitted by tick bites. It can cause intermittent joint pain and swelling, often affecting the knees.
  • Gout or Pseudogout: These conditions can cause acute, severe joint pain and should be considered, especially if the pain is monoarticular (affecting one joint).
• Rare Diagnoses
  • Relapsing Polychondritis: A rare autoimmune disorder that can cause cartilage inflammation, leading to joint pain, among other symptoms.
  • Sjögren's Syndrome: An autoimmune disorder that can cause joint pain, dry eyes, and dry mouth. It might not be as rare as other conditions in this category but is less common than RA or OA.
  • Mixed Connective Tissue Disease (MCTD): Overlaps with lupus, scleroderma, and polymyositis, and can present with joint pain and various other systemic symptoms.

Each of these diagnoses has a different set of diagnostic criteria and treatment approaches. A thorough clinical evaluation, including history, physical examination, and additional diagnostic tests (e.g., inflammatory markers, imaging studies), is necessary to determine the most likely diagnosis and appropriate management plan.