Differential Diagnosis for 25 yo with IBS, Recurrent Fleeting Pain in Ankles and Knees

• Single most likely diagnosis
  • Fibromyalgia: This condition is characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory, and mood issues. The absence of inflammation and normal X-rays, along with the patient's age and the nature of the pain, make fibromyalgia a plausible diagnosis. Its association with irritable bowel syndrome (IBS) also supports this consideration.
• Other Likely diagnoses
  • Hypermobility Syndrome: This condition involves joints that move beyond the normal range, which can lead to fleeting pains in various joints, including ankles and knees. It's often associated with IBS and could explain the patient's symptoms.
  • Seronegative Spondyloarthropathy (e.g., Ankylosing Spondylitis, Psoriatic Arthritis, Reactive Arthritis): Although these conditions typically present with inflammatory back pain and sometimes peripheral joint involvement, early stages or mild forms might not show significant inflammation on X-rays. The connection between these conditions and IBS, as well as the potential for fleeting joint pains, makes them worth considering.
• Do Not Miss diagnoses
  • Lyme Disease: Caused by the bacterium Borrelia burgdorferi, Lyme disease can present with intermittent joint pains, particularly in the knees, and can be associated with gastrointestinal symptoms. Given its potential severity and the importance of early treatment, it's crucial not to miss this diagnosis.
  • Osteonecrosis (Avascular Necrosis): This condition involves the death of bone tissue due to a lack of blood supply and can cause pain in the affected joints. It might not always show up on initial X-rays, making it a "do not miss" diagnosis due to its potential for severe and irreversible damage if not treated promptly.
• Rare diagnoses
  • Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. While rare, it could explain the joint pains and the association with IBS, given its impact on various bodily systems.
  • Sarcoidosis: A disease characterized by the growth of tiny collections of inflammatory cells (granulomas) in any part of the body — most commonly the lungs and lymph nodes — but can also affect joints. It's a rare consideration but should be kept in mind due to its potential for multi-system involvement.