The natural history of asymptomatic positron emission tomography: positive giant cell arteritis after a case of self-limiting polymyalgia rheumatica

Keywords Polymyalgia rheumatic Giant cell arteritis Temporal arteritis (TA) Histopathology RadionuclideimagingBlockmans et al. [1] showed that 31 % of patients withnewly diagnosed polymyalgia rheumatica (PMR) havepositron emission tomography (PET) signs of moderatevasculitis, especially in the subclavian arteries. Moreprominent vasculitic changes were found in 74 % ofpatients with giant cell arteritis (GCA) [2]. We report apatient with PMR who went into remission without steroidtherapy, but who experienced a relapse in the form ofasymptomatic ﬂuorodeoxyglucose (FDG)-PET-positiveGCA after two years.A 77-year-old woman presented in our hospital withcomplaints of acute onset lumbar pain and swelling/pain ofthe right wrist joint, left knee and right foot joint. TheC-reactive protein (CRP) level was 11.43 mg/dL, andthe erythrocyte sedimentation rate (ESR) was 136 mm/h.The patient was negative for rheumatoid factor and anti-cyclic citrullinated peptide antibody. FDG-PET/computedtomography (CT) revealed FDG accumulation in theshoulders, ischial tuberosities, and lumbar spinous pro-cesses, in addition to the symptomatic joints (Fig. 1a). Magnetic resonance imaging (MRI) of the knees and footjoints revealed synovitis. We initially considered thepatient’s condition to be enthesopathy, as the ischialtuberosities and lumbar spinous processes are consideredentheses. According to the European SpondyloarthropathyStudy Group criteria [3], we diagnosed the condition asspondyloarthritis (SpA) due to the asymmetrical synovitisof the lower extremities and enthesopathy. We treated thepatient with nonsteroidal anti-inﬂammatory drugs (NSA-IDs) and salazosulfapyridine. Within six months, theinﬂammatory response was negative, and her symptomsresolved.After approximately two years, the inﬂammatoryresponse was again positive (CRP 4.10 mg/dL, ESR124 mm/h), despite the lack of reported symptoms. FDG-PET/CT was performed to search for a focus. AlthoughFDG accumulation tended to be absent from the shoulders,ischial tuberosities, and lumbar spinous processes(Fig. 1b), marked FDG accumulation was observed in thelarge vessels and was predominant in the subcutaneousright temporal region (Fig. 2b). Head CT angiographyshowed hypertrophy of the right side of the superﬁcialtemporal arterial wall. Although the patient had none of thetypical symptoms of temporal arteritis (TA), such as newheadache, ocular symptoms including double vision andvisual loss or jaw claudication, we suspected TA. Biopsy ofthe temporal artery revealed a rupture of the internal elasticlamina of the temporal artery (Fig. 3a) and a granulomaassociated with the appearance of multinucleated giantcells in the tunica media (Fig. 3b), conﬁrming a diagnosisof GCA. Inﬂammatory and infectious diseases should beconsidered in the differential diagnosis of aortitis. Inﬂam-matory diseases, including Behc¸et’s disease, Cogan syn-drome, relapsing polychondritis, and sarcoidosis, wereunlikely because the clinical symptoms were inconsistentwith these diseases. Bacterial infections (including Sal-monella) were ruled out because blood cultures werenegative. Syphilis was unlikely based on the negative