To the Editor: We report on a case of fever of unknown originin which 18F-fluorodeoxyglucose (FDG) positron-emission tomography(PET) was instrumental in depicting cartilage inflammation,which eventually led to a histologically confirmed diagnosisof relapsing polychondritis. Relapsing polychondritis is a rareinflammatory disease that may affect cartilage throughout thebody, but the diagnosis may be challenging in the absence oftypical auricular or nasal involvement, as in the patient describedhere.1
A 67-year-old man presented with a 1.5-year history of persistentcough with clear secretions, progressive shortness of breath,sore throat, bloated stomach, low-grade fever, malaise, andweight loss. Physical examination revealed tenderness on allsternocostal junctions and in the laryngeal region. Vesicularbreath sounds were decreased. The erythrocyte sedimentationrate was 130 mm per hour, and the C-reactive protein level was20.0 mg per deciliter (normal level, <0.5). The white-cellcount was 15,000 per cubic millimeter, with 86% neutrophils.The lactate dehydrogenase level was 516 U per liter (normalrange, 240 to 480). All cultures and serologic tests were negative.The antinuclear factor level was normal, and the level of c-antineutrophiliccytoplasmic antibodies was slightly increased.
The patient's condition improved with the administration ofcorticosteroids for the treatment of asthma, but he did nothave a complete recovery. As part of a diagnostic workup, thepatient underwent whole-body PET with FDG (FDG-PET). The imagingstudy revealed marked tracer uptake in all rib cartilages, aswell as in the larynx, trachea, and major bronchi (Figure 1A).Surgical biopsy of the 12th rib cartilage, shown to be involvedon PET, provided histologic confirmation of the diagnosis.
Figure 1. Positron-Emission Tomographic (PET) Studies with 18F-fluorodeoxyglucose in a Patient with Relapsing Polychondritis.
Transverse slices at the level of the larynx (top) and coronal slices at the rib cartilages (middle) and through the tracheobronchial tree (bottom) show increased tracer uptake before the diagnosis of relapsing polychondritis (Panel A). The cartilaginous tracer accumulation is not visible during remission (Panel B).
Treatment with methylprednisolone and dapsone induced diseaseremission. After 5 months, while receiving a daily dose of 8mg of methylprednisolone, the patient had a relapse. The doseof methylprednisolone was increased to 32 mg, and cyclophosphamide(at a daily dose of 100 mg) was administered. At that time,severe retro-obstructive bilateral pneumonia developed. Antibioticswere temporarily added to the regimen, and endobronchial stentswere inserted. Nine months after his condition had been diagnosed,the patient again had a clinical and biochemical remission,and cartilaginous tracer accumulation had largely disappearedon a new PET study (Figure 1B).
Evidence supporting the pivotal role of FDG-PET in the diagnosisof fever of unknown origin is increasing steadily.2,3 The casewe describe illustrates the role of FDG-PET in the diagnosisof relapsing polychondritis, especially in patients who do nothave typical manifestations. By localizing sites of active inflammation,FDG-PET may guide the selection of a biopsy site.2 Like otherreported cases, this case shows the correlation between thefindings on FDG-PET and disease activity, as assessed by clinicaland laboratory measures.4
Frank De Geeter, M.D., Ph.D. Stefaan J. Vandecasteele, M.D.,Ph.D. Saint John's General Hospital 8000 Brugge, Belgium frank.degeeter{at}azbrugge.be
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