GENOVA, Italy—Positron emission tomography (PET) imaging could be a useful adjunct in the evaluation of steroid-resistant polymyalgia rheumatica (PMR), according to M. A. Cimmino, MD, and colleagues at the University of Genova, Italy. They report in Rheumatology the result of PET and 5-fluorodeoxyglucose (FDG)-PET scans in a series of eight such patients.1 The researchers suggest that such imaging might be particularly useful in PMR patients who also have otherwise undetected giant cell arteritis (GCA).

“I would suggest performing a FDG-PET scan in every patient with PMR complaints, who also has fever or considerable weight loss, to rule out large vessel vasculitis.”?Daniel Blockmans, MD, PhD
"We have performed PET in steroid-resistant PMR patients with the aim of ascertaining whether undetected vasculitic changes could explain steroid resistance. Diagnosing large-vessel vasculitis should be relevant in this setting, because patients may need increased doses of steroids and the addition of immunosuppressive drugs, as in case of concomitant GCA," Dr. Cimmino said.

The PET scans showed large-vessel vasculitis in three of the eight patients. But Daniel Blockmans, MD, who reviewed the study for Muscloskeletal Report, suspects that none of the study patients actually had “pure” PMR. “Since the clinical picture of GCA of the large vessels, without cranial symptoms and with a negative temporal artery biopsy, is insufficiently well known, most of these people might be diagnosed as suffering from PMR,” said Dr. Blockmans, who last year published the first prospective study of FDG-PET in patients with isolated PMR.  

“In that aspect, I would suggest performing a FDG-PET scan in every patient with PMR complaints, who also has fever or considerable weight loss, to rule out large vessel vasculitis. Another advantage of performing a PET scan in these patients is that you might rule out an underlying neoplastic process (although PET scan also gives false positive scans for tumor).”

Dr. Cimmino reported FDA-PET results for eight consecutive patients with steroid-resistant PMR with median age 73 years and mean disease duration of 69.4 months. They undertook the study because of reports that 31% of newly diagnosed PMR have signs of vasculitis. The investigators defined steroid-resistant PMR as disease that flared if prednisolone was withdrawn before 2 years or if the dose was tapered to <7.5 mg/day. Five of the eight patients had headaches or temporal tenderness suggestive of GCA, which had been confirmed by biopsy in one patient. PET scans showed large-vessel vasculitis in three of eight patients but not in the one patient with biopsy-confirmed GCA.

The three patients with PET-confirmed large-vessel vasculitis included
  • a 73-year-old woman with a 2-year history of fever, fatigue, pain in the cervical spine and girdles, and a systemic inflammatory laboratory response. Symptoms responded to prednisone 25 mg but flared when the dose was tapered. PET revealed aortitis. Symptoms and laboratory findings improved with methotrexate (MTX) 15 mg/week and prednisolone 12.5 and 18.75 mg on alternate days.
  • a 76-year old woman with girdle pain, weight loss, and temporal pain associated with elevated inflammatory markers. Symptoms responded to prednisolone 50 mg/day but recurred when the dose was tapered to 10 mg/day. PET scan after 4 years showed increased vascular uptake in all regions. Symptoms improved when MTX 15 mg/week was added to the regimen.
  • a 77-year-old woman with girdle pain, high-grade fever, weight loss, and elevated inflammatory markers. Symptoms responded to 16 mg/day of methylprednisolone but recurred when the steroid was tapered. PET showed increased uptake in the thoracic aorta spreading to the abdominal tract and in the initial part of the supra-aortic branches. Symptoms improved with a regimen of MTX 10 mg/week and prednisolone 12.5 mg/day.

The patients with positive PET findings also had higher CRP levels (146 mg/dL vs 44 mg/dL, P = .03) and ESR levels (103 mg/dL vs 65 mg/dL, P = .07).
 
“I believe that ‘pure PMR’ is mainly a (peri)synovitis of the shoulders, hips, and processi spinosi of the vertebral column,” Dr. Blockmans continued. “The patients Cimmino et al describe are, in my opinion, not ‘pure PMR’ patients but were probably from the start suffering from ‘GCA of the large vessels.’ I say this because I do not believe that ‘pure PMR’ patients have fever or weight loss, as the three patients of Cimmino et al.”

Translating research into practice

Dr. Blockmans treats patients with ‘pure PMR’ with a very low dose of steroids, starting with 12 mg/day for 2 weeks, then 8 mg/d, and tapering to stop after 6 months. However, Dr. Blockmans emphasized that this dose is too low to effectively treat large vessel vasculitis.

“I do not think that in every day clinical practice, much imaging is needed if the clinical picture is perfectly compatible with ‘pure PMR,’ so only morning stiffness and pain in the shoulder, hip girdle, and back, and if there is prompt amelioration after one dose of 8 mg of methylprednisolone. In all other cases, I would perform at least a chest radiography and an abdominal ultrasound and sometimes a PET scan, to rule out other disorders,” Dr. Blockmans explained.

References

1. Cimmino MA, Zampogna G, Parodi M. Is FDG-PET useful in the evaluation of steroid-resistant PRM patients? Rheumatology. 2008;47:926-927.
2. Blockmans D, De Ceuninck L, Vanderschueren S, et al. Repetitive 18-fluorodeoxyglucose positron emission tomography in isolated polymyalgia rheumatica: a prospective study in 35 patients. Rheumatology. 2007;46:672-677.