Diagnosis: Glial choristoma of the middle ear
Choristomas are not neoplasms. Rather, they represent anatomically displaced tissues that have resulted from a developmental defect that occurred during embryogenesis.1 In effect, histologically normal tissues are encountered in anatomically unexpected sites. Brain tissue that is encountered in some extracranial sites is referred to as glial heterotopia. Glial heterotopia usually occurs along the midline of the head and neck, typically involving the nasopharynx, soft palate, lips, tongue, and tonsils.2 The nose (nasal glioma) is the most commonly involved site.3 As choristomas of the middle ear do not occupy a midline location, they are much more likely to be composed of salivary gland tissue (salivary gland choristoma) than of glial tissue.4
Pathology Quiz Case: Diagnosis. Arch Otolaryngol Head Neck Surg. 2005;131(4):364. doi:10.1001/archotol.131.4.364
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