The Use of Functional Imaging in a Patient with Head and Neck Paragangliomas

Abstract

A 21-yr-old male presented to the National Institutes of Health with five head and neck paragangliomas, found after treatment for chronic ear infections. Symptoms experienced by the patient included constant right ear pain, mild yellowish discharge from the right ear, decreased hearing, and a constant vibration sound on the right side but no symptoms related to catecholamine excess. On evaluation five paragangliomas were found on anatomical imaging (computed tomography and magnetic resonance imaging) as follows: 2.7- × 1.6-cm right carotid body tumor; 3.1- × 2.6-cm left carotid body tumor; 3.6- × 2.4-cm left glomus vagale tumor; 1.0- × 1.0-cm tumor in the left jugular fossa; and a 2.1- × 1.8-cm tumor in the right jugular fossa, which had caused extensive bone destruction involving the bony walls of the jugular fossa, the external auditory canal, the condylar fossa of the temporal mandibular joint, and the hypotympanic cavity of the right middle ear. Biochemistry (plasma fractionated catecholamines and metanephrines; 24 h fractionated urinary catecholamines and metanephrines) was unremarkable except for elevation of plasma dopamine to 437 pg/ml (reference range 3–46 pg/ml) and urinary dopamine to 431 μg per 24 h (reference range 65–400 μg per 24 h). Genetic testing revealed a mutation (p.Pro81Leu) in the succinate dehydrogenase subunit D gene. Head and neck paragangliomas are often biochemically silent (normal catecholamine and metanephrine values), making imaging a very important diagnostic tool (1,2). Here we present a patient whose head and neck paragangliomas were localized on computed tomography (CT) (Fig. 1​1)) and show avid uptake with four functional imaging techniques: 18F-fluorodihydroxyphenylalanine (18F-FDOPA) positron emission tomography (PET) (Fig. 2A​2A);); 18F-fluorodopamine (18F-FDA) PET/CT (Fig. 2B​2B);); 18F-fluoro-2-deoxy-d-glucose (18F-FDG) PET/CT (Fig. 2C​2C);); and 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy (Fig. 2D​2D).). Two of these modalities, 18F-FDA PET/CT and 123I-MIBG scintigraphy, are paraganglioma specific, targeting the norepinephrine transporters expressed in these tumors (3,4). Although 18F-FDG and 18F-FDOPA PET are not paraganglioma-specific imaging modalities, their efficacy for the localization of these tumors is represented here. 18F-FDOPA PET, in particular, showed avid uptake in all five tumors and should be considered a good imaging technique for head and neck paragangliomas, as previously reported (5). As demonstrated here, multiple imaging modalities, both anatomical and functional, can be used for the accurate localization of head and neck paragangliomas. However, because CT imaging is nonspecific for paragangliomas, functional imaging modalities are a good tool for confirming in the diagnosis of head and neck paragangliomas. Figure 1 Coronal reconstructed CT of the neck. There are five tumors identified: right (1) and left (2) glomus jugulare tumors; a left glomus vagale tumor (3); and left (4) and right (5) carotid body tumors. All five tumors demonstrate homogeneous enhancement. ... Figure 2 A, 18F-FDOPA PET. B, 18F-FDA PET/CT. C, 18F-FDG PET/CT. D, 123I-MIBG scintigraphy. Four functional imaging modalities were used to localize five head and neck paragangliomas: right (1) and left (2) glomus jugulare tumors; a left glomus vagale tumor ( ...