Pathology of the Head and Neck

50 A. Cardesa · L. Alos · A. Franchisinuses. Histologically, they are similar to paragangliomaselsewhere [12, 98, 187].22.10.10 Juvenile AngiofibromaabFig. 2.8. Juvenile angiofibroma. a Polypoid mass of white-redcut surface and rubbery consistency. b Vascular elements embeddedin fibrous tissue showing intravascular microembolisation, atreatment modality prior to surgeryentiate neurofibromas from schwannomas of the sinonasalmucosa. Neurofibromas should also be distinguishedfrom myxomas, which are S-100 protein-negative.2.10.8 MeningiomaICD-O:9530/0Meningiomas of the sinonasal tract may extend directlyfrom the central nervous system or arise from ectopicextracranial tissue. Although always rare, they are morecommonly seen in the orbit, ear and skin of the head andneck than in the sinonasal tract. Histologically, they aresimilar to meningiomas elsewhere, the meningothelialtype being the most frequent. Sinonasal meningiomastend to occur in younger patients than intracranial meningiomas[118, 203].2.10.9 ParagangliomaICD-O:8680/1There are few reports on nasal paragangliomas. The tumoursoriginate in the middle turbinates and ethmoidICD-O:9160/0Juvenile nasopharyngeal angiofibroma arises in theconfluence of the posterolateral nasal wall and thelateral nasopharynx and occurs almost exclusively inmales during adolescence [90, 125]. The tumour is sessileor polypoid (Fig. 2.8a) and is histologically benign,but has a tendency to recur and is locally destructive,causing pressure necrosis of adjacent soft tissue andbone. It may occasionally extend into paranasal sinuses,orbit and cranial fossae. It is composed of vascular andfibrous elements in varying proportions. The vessels inthe superficial portions of the tumour are mainly gapingcapillaries that may become compressed with increasingstromal fibrosis. Thick-walled vessels withoutelastic membranes and with irregular, incomplete orabsent muscle coats and focal intimal thickenings areusually present in the deeper portions of the tumour.These vessels resemble those normally seen in the submucosaof the nasal conchae. The vascular elements areembedded in fibrous tissue, which varies in cellularityand collagenisation. Stellate fibroblast-like cells are oftenpresent close to the blood vessels. The fibroblasticcells of nasopharyngeal angiofibroma are stronglypositive for testosterone receptors [120]. Ultrastructurally,the nuclei of angiofibroma contain characteristicdense granules [251]. Occasionally, the fibroblasts mayexhibit cytologic atypia, and some of these cells maybe multinucleated, but mitosis is rare. Mast cells maybe numerous. There may be focal thrombosis, haemorrhageand chronic inflammatory reaction. With theadvent of preoperative selective embolisation, iatrogenicemboli (Fig. 2.8b) are increasingly encounteredin resected specimens [232]. For more details on thistumour see Chap. 6.2.11 Malignant Sinonasal TumoursMalignant sinonasal tumours represent less than 1% ofall cancers seen in humans and about 3% of all malignanciesof the head and neck region [160]. Despite thelow rate of malignancy arising in the sinonasal tract, agreat variety of histological types of tumours may befound [216, 226]. The use of electron microscopy andmore recent advances in immunohistochemistry andmolecular biology have made it possible to refine thecriteria for their correct recognition.Geographical differences in the relative frequencyof certain histological types of malignant sinonasaltumours may be related to variations in the exposure