Pathology of the Head and Neck

Ear and Temporal Bone Chapter 8 2478.3.1.3 Unusual Inflammatory LesionsTuberculous otitis media is an unusual form of chronicotitis media, which is generally associated with activepulmonary tuberculosis. In the initial stages multipleperforations of the tympanic membrane develop.Granulations in the middle ear may appear pale andare often profuse. Complications, especially involvementof the facial nerve, are more frequent than in thecommoner form of chronic otitis media. The diagnosisis usually made by histopathological examination ofbiopsy material from middle ear contents. This is oftendelayed because surgeons are reluctant to take biopsiesfrom cases of chronic otitis media that seem fairly typical.Culture of middle ear inflammatory tissue may producetubercle bacilli. Histological examination showstuberculoid granulation tissue composed of epithelioidcells, Langerhans giant cells and areas of caseation situatedin the middle ear mucosa. There is much bone destruction.Acid-fast bacilli are found with difficulty inthe granulomatous material.8.3.2 Neoplasmsand Lesions ResemblingNeoplasms8.3.2.1 Choristoma(Salivary Gland, Glialand Sebaceous Types)A hamartoma is a focal overgrowth, in improper proportions,of tissues normally present in that part of thebody. A choristoma is similar to hamartoma, exceptthat the tissues of which it is composed are not normallypresent in the part of the body where it is found.Choristomas are occasionally seen in the middle ear.They are composed of one or other of three types oftissue: salivary gland, glial or sebaceous glandular tissue.Salivary gland choristomas consist as a rule of mixedmucous and serous elements like the normal submandibularor sublingual gland, but unlike the parotidgland. The lesion typically consists of a lobulated massof histologically normal salivary gland tissue in the middleear attached posteriorly in the region of the oval window.Frequently, the mass is intimately associated withthe facial nerve. There are usually absent or malformedossicles [44].Glial choristomas are composed largely of astrocyticcells with large amounts of glial fibrils, the identityof which may be confirmed by immunohistochemicalstaining for glial acidic fibrillary protein. When suchmasses are identified in biopsy material from the middleFig. 8.13. Adenoma of the middle ear. Reproduced from Michaelsand Hellquist [68]ear a bony deficit with consequent herniation of braintissue into the middle ear should be ruled out [53]. Threecases of heterotopic brain tissue in the middle ear associatedwith cholesteatoma have been reported [62]. It ispossible that in all three, brain herniation occurred as aresult of inflammatory damage to the tegmen tympani.Spontaneous herniations of brain (encephaloceles) mayoccur into the middle ear through a congenital deficiencyof the tegmen or other sites [47].A case of sebaceous choristoma of the middle ear hasbeen described [82].8.3.2.2 AdenomaICD-O:8140/0Adenoma is the commonest neoplasm of the middle ear.The epithelium of the middle ear has a propensity towardsgland formation in otitis media (see above) andadenoma would seem to represent a benign neoplastictransformation of the epithelium along the same lines.The neoplasm has been described as being white, yellow,grey or reddish brown at operation and unlike paragangliomais usually not vascular. It is usually situatedin the middle ear cavity, sometimes extending into themastoid. It seems to peel away from the walls of the surroundingmiddle ear with ease, although ossicles maysometimes be entrapped in the tumour mass and mayeven show destruction.Adenoma is formed by closely apposed small glandswith a “back to back” appearance (Fig. 8.13). In someplaces a solid or trabecular arrangement is present.Sheet-like, disorganised areas are seen in which theglandular pattern appears to be lost. This may be artefactualand related to the effects of trauma used intaking the biopsy specimen on the delicate structure ofthe cells, but the appearance may erroneously lead oneto suspect malignancy. The cells are regular, cuboidalor columnar and may enclose luminal secretion. A dis-