The role of positron emission tomography for the diagnosis and follow up of a patient with sarcoidosis and Takayasu arteritis.

To the Editor: Takayasu arteritis (TA) is an uncommon chronic granulomatous disease of the large vessels. Sarcoidosis is also a systemic granulomatous disorder occasionally associated with vasculitis. Although it is not clear whether there is a pathogenetic association, the concurrence of sarcoidosis and TA has been previously described in 5 case reports. (1) We present a patient diagnosed as having both sarcoidosis and TA. FDG-PET ([.sup.18.F]-fluorodeoxyglucose positron emission tomography) aided in the diagnosis of active disease and was also used to monitor the effectiveness of treatment.

A 30-year-old woman was admitted with cough, fever, arthralgias, and acute weight loss. The diagnosis of sarcoidosis was made histologically. Computed thorax tomography revealed stage II sarcoidosis. Treatment was started with 32 mg/d of methylprednisolone. The patient ceased her medication and was lost to follow-up. Six months later, she was readmitted with swelling and pain on the left side of the neck. Except for the tenderness of the neck on palpation, she had a normal physical examination. Erythrocyte sedimentation rate (ESR) was 45 mm/h, and C-reactive protein (CRP) level was 20 mg/dL. Her lungs were clear on chest x-ray. Neck ultrasonography and tomography were unremarkable. Digital subtraction angiography revealed a slight thickening of the left common carotid artery. FDG-PET scanning demonstrated increased uptake in the ascending aorta and bilateral carotid arteries. The patient was diagnosed with TA and was treated with methylprednisolone 40 mg/d and azathioprine 150 mg/d. After six months of therapy, the patient was asymptomatic, and a murmur was audible over the left subclavian artery. ESR level decreased to 22 mm/h. A control FDG-PET revealed normal uptake in the involved vessels, suggesting complete disappearance of the clinical inflammatory process.

This case reveals that sarcoidosis and TA can possibly coexist, and this may indicate a potential causal relationship in the pathogenesis. Our experience emphasizes a need for a prospective evaluation of this association. In addition, FDG-PET may be a useful noninvasive tool in the diagnosis and follow-up of TA. Although timely diagnosis of TA is undoubtedly important to prevent a devastating outcome, angiography is not reliable to exhibit vascular inflammation, especially in the prepulseless phase, where the patients do not fulfill the American College of Rheumatology criteria for TA. (2)

FDG-PET has recently been investigated to facilitate the diagnosis and monitor disease activity in large vessel vasculitis. (3-5) Webb et al demonstrated that FDG-PET had a sensitivity and a specificity of 92% and 100% in detecting active and inactive TA disease, respectively. (3) Although mostly conducted in a low number of patients, the studies showed that FDG-PET may also be useful in the evaluation of response to treatment. (3-5) The advantage of this technique is enhanced, particularly during the early phase of the disease when angiography is unremarkable.

Nurdan Kokturk, MD

Haluk Turktas, MD

Department of Pulmonary Medicine

Mehmet Akif Ozturk, MD

Division of Rheumatology, Department of Internal Medicine

Handan Aksoy, MD

Department of Pulmonary Medicine

Tamer Atasever, MD

Department of Nuclear Medicine

Gazi University, School of Medicine

Ankara, Turkey

References

1. Weiler V, Redtenbacher S, Bancher C, et al. Concurrence of sarcoidosis and aortitis: case report and review of the literature. Ann Rheum Dis 2000;59:850-853.

2. Arend WP, Michel BA, Bloch DA, et al. The American College of Rheumatology 1990 criteria for the classification of Takayasu arteritis. Arthritis Rheum 1990;33:1129-1134.

3. Webb M, Chambers A, AL-Nahhas A, et al. The role of 18F-FDG PET in characterising disease activity in Takayasu arteritis. Eur J Nucl Med Mol Imaging 2004;31:627-634.

4. Andrews J, AL-Nahhas A, Pennell DJ, et al. Non-invasive imaging in the diagnosis and management of Takayasu's arteritis. Ann Rheum Dis 2004;63:995-1000.

5. Moreno D, Yuste JR, Rodriguez M, et al. Positron emission tomography use in the diagnosis and follow up of Takayasu's arteritis. Ann Rheum Dis 2005;64:1091-1093.

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