HSC Section 8_April 2017

Jugular Paragangliomas

Fig. 1. Otoscopic examination demonstrating a red mass behind an intact tympanic membrane.

IMAGING

A careful review of fine-cut temporal bone computed tomography (CT) and MRI with gadolinium is critical to differentiating jugular foramen tumors. The most common le- sions to involve the jugular foramen are JP, meningiomas ( Fig. 2 ), and lower cranial nerve schwannomas ( Fig. 3 ). Metastatic disease and endolymphatic sac tumors may also secondarily involve this region ( Fig. 4 ). On CT and MRI, JPs demonstrate a diffusely infiltrative pattern of disease resulting in bony destruction and early erosion of the jugulo–carotid spine ( Fig. 5 ). Vascular flow voids within the tumor result in a characteristic salt-and-pepper appearance on T1 and T2 weighted MRI, and the tumor avidly enhances with contrast administration ( Fig. 6 ). Although not completely reliable, most JPs demonstrate middle ear extension, while meningiomas and schwannomas rarely do so. In contrast, meningiomas commonly demonstrate dural tails with en pla- que growth and are often associated with underlying hyperostosis. Finally, schwanno- mas often “dumbbell” between the neck and posterior fossa, with a bottle neck at the jugular foramen. CT generally reveals a widened sharply demarcated jugular foramen without bony destruction. 14,15

TUMOR CLASSIFICATION

Multiple proposed classifications have been used, and none has gained universal acceptance. Tumor classifications described by Fisch and Glasscock and Jackson are the most commonly used. 16–18

GENETIC SCREENING

Familial head and neck paragangliomas are associated with germline mutations in genes encoding subunits of succinate dehydrogenase (SDH), which plays a role in the Krebs cycle. Though genetic evaluation of patients with head and neck paragan- gliomas is emerging as an important topic in the diagnosis and management of these tumors, the most cost-effective way of screening at-risk patients is not yet clear. Because 30% of sporadic head and neck paragangliomas are caused by germline

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