Inflammatory Polyarthritis

Patterns of polyarthritis.  Can you identify the most likely diagnosis based on these distributions? (answers below)

Patterns of polyarthritis.  Can you identify the most likely diagnosis based on these distributions?
(answers below)

Today we discussed a term that was new to many of us, "Undifferentiated Arthritis."  Early in the course of an inflammatory arthritis, the etiology can be quite difficult to clinically diagnose especially between infectious and rheumatologic diseases (which tend to be criteria-based diagnoses).  This is where the term "Undifferentiated Early Inflammatory Arthritis" or "Undifferentiated Arthritis" arose to capture this subset of patients in the first weeks to year of their course.  This lends to the question as to whether or not to use DMARDs at this early stage, despite the lack of a specific diagnosis.  Currently, there is no robust data to support long term or early treatment, though it may slow progression of disease in Undifferentiated Arthritis, especially if there are other risk factors for RA (like a family history, or suspicion of CVID as we discussed in this case).

The winning answers to Residency Feud today were the top 5 viral causes for inflammatory arthritis:
   -Hepatitis B&C
   -Parvovirus
   -Rubella
   -Alphaviruses (including Chikungunya)
   -Dengue

As referenced during report today, this JAMA article provides some helpful likelihood ratios in diagnosing septic arthritis: Does This Patient Have Septic Arthritis?

Answers to the above question: From left to right:
RA (MCP, PIP, MTP and other joints in a symmetrical fashion)
Psoriatic Arthritis (PIP, DIP and large joints in an asymmetrical fashion)
Ankylosing Spondylitis (axial skeleton and large peripheral joints in an asymmetrical fashion)
OA (DIP, base of thumb, knees, hips, lumbar and cervical spine)