Pathology of the Head and Neck

Nasopharynx and Waldeyer’s Ring Chapter 6 179papillomas have an increased potential for recurrence,which is higher in the nasopharynx than in the sinonasallocation. This probably reflects the high rate of incompleteinitial removal due to the unexpected nature of thelesion and the difficult nasopharyngeal anatomy. As ina sinonasal location, inverted papillomas are at risk ofmalignant transformation. For a detailed description ofinverted papillomas, see Chap. 2.6.2.4.4 Solitary Fibrous TumouraICD-O:8815/0Solitary fibrous tumours are exceptionally rare in theupper respiratory tract. In the nasopharynx, only 4 caseshave been described to date [96, 122, 201].6.2.4.5 ParagangliomabICD-O:8680/1Paraganglioma (or chemodectoma) arise in the head andneck region most commonly in the carotid body, glomustympanicus and glomus jugulare. They are extremelyrare in the nasopharynx with about 20 cases described(for review see [101]), but need to be considered whenprofuse haemorrhage and a pulsatile mass are encounteredin the nasopharynx. These slowly enlarging, painless,firm, encapsulated tumours are characterised bynests (so-called Zellballen) of small to medium-sizedpale monomorphous cells with prominent, roundedhyperchromatic nuclei and a prominent network of endothelialcell lined vascular channels (see also Chaps. 8and 9).6.2.4.6 MeningiomacFig. 6.4. Respiratory epithelial adenomatoid hamartoma. a Thisfragmented surgical specimen of polypoid hamartoma displaysnumerous fluid and mucin filled cysts. b The surface is lined bytall columnar respiratory epithelium and there are widely spacedacinar proliferations embedded in a fibrous stroma. c The acinarproliferations are in continuity with invaginations of the surfacerespiratory epithelium and recapitulate either seromucous glands.The basement membrane is typically thickenedresponded histologically to a multilayered, transitionaltypeepithelium with foci of respiratory and squamousepithelium growing endophytically into the underlyingloose and myxoid stroma. Nasopharyngeal invertedICD-O:9530/0Among the rarest tumours of the nasopharynx are extracranialmeningiomas [162]. In a series of 30 extracranialmeningiomas, 3 were located in the nasopharynx[188]. There is only a single case report of a primary tonsillarectopic meningioma [107]. Extracranial meningiomasshow the same histological subtypes, differentiationand prognosis as intracranial meningiomas, but the syncytial(meningothelial) subtype predominates. For meningiomasat other sites in the head and neck area, seeChaps. 2, 8 and 10.6.2.4.7 Glandular Retention CystsGlandular retention cysts are rather common in the oroandnasopharynx and some may become large enoughto mimic nasopharyngeal tumours. They arise from di-