Psoriatic Arthritis – often misdiagnosed

Doctors know that over time, tendinitis and bursitis can lead to pain in the muscles surrounding an affected joint/tendon/bursa.  It’s just a consequence of long-term inflammation.

This pain can interfere with sleep.  That seems obvious, but it’s amazing how many people don’t realize there’s a connection.  If your shoulder hurts, even if you manage to fall asleep, every time you roll over on it, the pain can awaken you.  Likewise if the pain is in your hip.  In fact, regardless of pain’s cause, it’s not at all unusual for pain to lead to sleep loss.  To make matters worse, loss of sleep magnifies pain.

This is why it is so important for tendonitis and bursitis to be diagnosed quickly.  The diagnosis leads to treatment:  physical therapy & anti-inflammatories (and sometimes muscle relaxants).  If you get a good physical therapist and do your prescribed exercises religiously, the problem can usually be well-managed and the pain will go away.

Unfortunately, sometimes doctors miss a tendonitis/bursitis diagnosis.  If the patient had no injury causing the problem, the doctors might miss the diagnosis.


Undiagnosed tendonitis in both shoulders eventually leads to muscle aches in the upper back and both arms.  Undiagnosed tendonitis in both Achilles tendons leads to muscle aches in the lower legs.  Undiagnosed bursitis in the hips leads to muscles aches in the thighs.  At this point, many doctors give up and call it “fibromyalgia” (unexplained muscle aches in all four quadrants), and move on to patients they can help. This, despite the fact that a diagnosis of bursitis and/or tendonitis would perfectly explain all the symptoms1.

Or maybe it isn’t tendonitis/bursitis.  Maybe it’s vague back pain.  Maybe it comes and goes — flaring up for a while, then disappearing.  Maybe it’s not symmetric (only one shoulder/hip/knee instead of both).

All of these situations call for a closer investigation of family history for symptoms of psoriasis.  Note, however, that at least 15% of people with psoriatic arthritis do not have skin psoriasis.

The diagnosis of psoriatic arthritis (PsA) often is missed, partly because patients may present with inflammatory spinal pain, tendinitis, enthesitis, or dactylitis rather than a “true arthritis.”
Jaya Philipose, MD and Atul Deodhar, MD

Many doctors won’t make a PsA diagnosis without seeing visible evidence of psoriasis.  They might not realize the criteria for diagnosis.  ClASsification criteria for Psoriatic ARthritis (CASPAR) requires inflammatory articular disease.  Spine pain, enthesitis, or tendonitis are sufficient; visible swelling is not required; neither is symmetry.  If that criteria is met, then at least three points from the following five categories are sufficient for a diagnosis of psoriatic arthritis:

  1. Psoriasis — either
    1. current psoriatic skin or scalp disease diagnosed by a rheumatologist or dermatologist (2 points), or
    2. personal history of psoriasis (1 point), or
    3. 1st degree (parent, child, sibling) or 2nd degree (grandparent, grandchild, aunt, uncle, nieces, nephews, half-siblings) blood relative with psoriasis (1 point)
  2. Psoriatic nails (1 point)
  3. Negative RF blood test (1 point)
  4. Dactylitis (swollen “sausage” fingers/toes)– current or history (1 point)
  5. New bone formation near joints visible on x-ray (1 point)

Under this criteria:

  • a person with enthesitis, a negative RF test (1 pt), and mild scalp psoriasis (2 pt) should be diagnosed with PsA.
  • a person with mild inflammatory spine pain, a first or second-degree relative with psoriasis (1 pt), evidence of new bone formation on x-rays (1 pt), and negative RF (1 pt)  should be diagnosed with PsA
  • a person with tendinitis, psoriatic skin disease (2 pt), psoriatic nails (1 pt), and a positive RF (0 pt) meets the criteria for PsA.

Although doctors used to consider psoriatic arthritis as a sub-type of rheumatoid arthritis, that is no longer the case.  Psoriatic arthritis is a separate condition with distinct diagnostic criteria.


1There is a reason that many “fibromyalgia” patients thrive with physical therapy.  They do not actually have unexplained muscle pain.  Their muscle pain is caused by tendonitis and bursitis.  Treating the tendonitis/bursitis cures the muscle pain.  This in turn makes it possible for the patient to get restful sleep.

Note this is not the only possibility for a “fibro” diagnosis.  Another common missed diagnosis is heart disease.  Cardiologists have been known to tell patients that they do not have fibro; all their symptoms are due to heart disease, and the symptoms resolve if the heart disease is well-treated.


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