Chapter 30 - Tumors of the Ear

Abstract

Neoplasms and mass-forming lesions of the ear are very uncommon and in general are divided into anatomic compartments: external ear (including external auditory canal), middle ear, and inner ear. There is a very broad spectrum of neoplasms that may arise from skin, adnexal structures, mucosal linings, and mesenchymal elements, resulting a very wide differential diagnostic consideration required to reach an accurate interpretation. To fully understand these diagnoses, a comprehensive integration of the anatomic relationships, imaging findings and surgical approaches must be employed and correlated with the histology findings. The temporal bone is one of the most compact and complex anatomic structures in the body, housing the hearing and vestibular organs, all in close proximity to the brain and other vital structures. In these sites, high resolution imaging studies are essential, providing valuable “gross” descriptions needed in determining the type of lesion present, recognizing that computed tomography and magnetic resonance yield complimentary information. Most of the neoplasms affecting the external ear are derived from the skin (basal cell carcinoma, squamous cell carcinoma), but rhabdomyosarcoma are not common in this site. However, squamous cell carcinoma also arises from the middle and/or inner ear. These complicated three-dimensional specimens are often challenging to assess. First branchial cleft anomalies may present with sizeable masses, even though a developmental disorder. The ceruminous neoplasms (from modified apocrine glands) are peculiar and specific to the external auditory canal, often challenging due to fragmentation and small biopsy samples. Due to practical limitations, middle and inner ear lesions are generally combined, as the precise origin may be artificial when large. Cholesteatoma is a relatively common, benign, but destructive temporal bone lesion, a result of a multistep process that can yield significant morbidity. Paraganglioma is commonly familial or syndrome associated, with SDHB immunohistochemistry aiding the pathologist to screen for this cohort of patients. Paraganglioma are evaluated by a risk stratification, aiding in their management. Middle ear adenoma is a unique dual glandular and neuroendocrine neoplasm, often bland histologically, but with an infiltrative appearance. Schwannomas are relatively common in the inner ear, while meningiomas frequently affect the temporal bone. Endolymphatic sac tumors are rare, but have a unique clinical association with von Hippel-Lindau disease and show a characteristic immunophenotype. This chapter presents the salient clinical, imaging and pathological features, richly supported by high-quality images and illustrations, to aid in accurately diagnosing otologic disorders.