Differential Diagnosis for Spondyloarthritis

The differential diagnosis for spondyloarthritis can be complex, given the variety of conditions that can present with similar symptoms. Here's a breakdown of potential diagnoses into categories:

• Single Most Likely Diagnosis

  • Ankylosing Spondylitis (AS): This is the most common form of spondyloarthritis, characterized by chronic inflammation of the spine and sacroiliac joints, leading to pain and stiffness. It often starts in young adulthood and can lead to fusion of the spine if not properly managed.

• Other Likely Diagnoses

  • Psoriatic Arthritis (PsA): A condition that combines the swollen, scaly skin of psoriasis with joint pain and arthritis. Symptoms can range from mild to severe and may include psoriatic skin lesions, nail changes, and eye inflammation.
  • Reactive Arthritis (ReA): Previously known as Reiter's syndrome, this form of arthritis occurs as a reaction to an infection elsewhere in the body, often in the gastrointestinal tract or the urethra. It typically affects the knees, ankles, and feet.
  • Enteropathic Arthritis: Associated with inflammatory bowel diseases like Crohn's disease and ulcerative colitis, this condition can cause joint pain and inflammation, often in response to bowel disease activity.
  • Undifferentiated Spondyloarthritis (uSpA): This diagnosis is used when symptoms of spondyloarthritis are present, but the criteria for a specific type (like AS or PsA) are not fully met. It can be a precursor to other forms of spondyloarthritis.

• Do Not Miss Diagnoses

  • Infectious Spondylodiscitis: An infection of the intervertebral disc space, which can be caused by bacteria or fungi. It requires prompt antibiotic treatment to prevent serious complications, including paralysis or death.
  • Spinal Epidural Abscess: A collection of pus that forms in the space surrounding the spinal cord, which can compress the cord and cause neurological deficits. It is a medical emergency requiring immediate surgical intervention.
  • Cauda Equina Syndrome: A condition that occurs when the nerves in the spinal canal are compressed, leading to pain, numbness, and weakness in the legs, as well as bladder and bowel dysfunction. It is a surgical emergency.

• Rare Diagnoses

  • SAPHO Syndrome: A condition characterized by Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis. It involves the skin and skeletal system and can mimic other forms of spondyloarthritis.
  • Juvenile Spondyloarthritis: A term that encompasses various forms of spondyloarthritis that begin in childhood, including juvenile ankylosing spondylitis, enthesitis-related arthritis, and psoriatic arthritis. These conditions can have different presentations and prognoses than their adult counterparts.

Each of these diagnoses has distinct clinical features, and a thorough medical history, physical examination, and diagnostic tests (such as imaging and blood work) are essential for accurate diagnosis and management.