When Bone Pain Isn’t What You Think
December 1, 2021
Each year Seattle Children’s Rheumatology program treats several hundred patients who have chronic recurrent multifocal osteomyelitis (CRMO), also known as chronic nonbacterial osteomyelitis (CNO).
What is CRMO?
CRMO is an autoinflammatory disease that causes pain and damage to the bone from inflammation. Pain most commonly occurs in the long bones of the leg but can show up anywhere on the skeleton, in either a single site or multiple sites. CRMO has no cure but is a treatable disease that has good outcomes with timely diagnosis and close monitoring by rheumatologists.
Patients who are diagnosed early and appropriately treated will have normal growth and physical capacities. Delayed diagnosis or treatment can lead to permanent complications such as spine fractures, bone overgrowth or deformity, prolonged pain and the associated emotional challenges.
CRMO is an underrecognized disease, often mistaken for growing pains or symptoms of infection or cancer.
What does CRMO look like in a patient?
A typical patient is 9 to 12 years old (but can present as young as age 3) and presents with chronic recurrent bone pain with no obvious swelling of the bone or joint. Their symptoms often come and go over time. X-rays and bloodwork are often normal. Patients are likely to have very focal pain on exam. Kids with CRMO are also more likely to have inflammatory bowel disease, severe acne or psoriasis.
How do I know it’s not growing pains?
That’s a good question. Growing pains occur at night, but so do CRMO pains. Kids with CRMO may limp or limit activity, which is not typical of kids with growing pains. Growing pains tend to come in clusters that are fairly brief, i.e., for a few days or a week at a time, whereas CRMO pain can last for an entire month. If the child has daytime pain in the same spot as their nighttime pain, or if they have any joint function limitation during exam, that increases suspicion of CRMO. If the pain symptoms have gone on for less than six weeks, however, we are hesitant to give a CRMO diagnosis.
Why is CRMO easily missed?
Several factors often slow down a CRMO diagnosis.
- Many providers aren’t familiar with the disease so they don’t recognize it, nor do they look for it.
- CRMO can look a lot like growing pains.
- X-rays and labs are often normal.
- It’s a diagnosis of exclusion; many tests may be required, including MRI, bone scan and bone biopsy, but none is completely confirmatory
- When an MRI shows bone inflammation, a PCP will commonly suspect infection or cancer first and refer to an oncologist or orthopedist. A CRMO diagnosis is often pursued last or not at all.
When you suspect CRMO
If a child has bone pain for more than six weeks and you suspect CRMO, we recommend you order an MRI and labs, including CBC with diff, ESR, CRP, alkaline phosphatase, vitamin C and D, PTH, cal, phos, LDH and uric acid.
- If there are any red flags* refer to Oncology or Orthopedics (specifically an orthopedic tumor surgeon).
- If there are no red flags and labs are normal, suspect CRMO and refer to Rheumatology.
- If there are no red flags but patients have had premature loss of infant teeth and alkaline phosphatase level was low, you may refer to Endocrinology for hypophosphatasia.
- Call our Provider-to-Provider Line and ask to speak with the on-call rheumatologist if you have questions or are unsure: 206-987-7777.
See our CRMO algorithm for details.
*Red flags: acute onset of pain; ESR >60; CRP >3 mg/dL; elevated LDH; elevated uric acid; cytopenia; traveling or exposure history concerning for tuberculosis; pain in an unusual site such as skull or diaphysis of long bones; or imaging shows mass, infarction or abscess
A faster path to diagnosis
An initial MRI of the symptomatic body parts will reveal the inflammation and accelerate the diagnostic process. Please note that including both legs is much more important and useful than giving contrast due to the nature of symmetrical and multifocal pattern of this disease in >60% of affected patients. Insurance companies frequently deny authorization for an MRI. To avoid this, we recommend you:
- Obtain the X-ray first and reference it in the appeal letter.
- Submit a physician letter with the MRI request. We have a template letter you can use and tailor to your patients.
Treatment for CRMO
Some children with CRMO can be managed with NSAIDs alone, while others require one or more additional medications such as methotrexate, sulfasalazine and others. Children with CRMO will need follow-up care in adulthood with a rheumatologist due to the lifelong possibility of disease flare.
Seattle Children’s has the only CRMO program in the Western states for children and teens with this rare disorder.
When referring to Rheumatology for CRMO
- If your patient’s appointment with the CRMO team is more than a month out, you are welcome to call us to review their history and possibly expedite their appointment.
- Consider recommending over-the-counter NSAIDs to help manage their pain before their appointment with us.
- If your patient’s bone pain curtails their physical activity, consider also referring them to sports physical therapy for muscle strengthening and conditioning.
- Help the family to get their MRI authorized.
CRMO clinic locations and telehealth
Our team sees patients once a week at Seattle Children’s main campus and Bellevue clinic.
We see patients in Montana, Idaho and Alaska via telehealth, including for an initial quick intake to help the family get insurance authorization for a whole-body MRI.