Pathology of the Head and Neck

216 N. Gale · A. Cardesa · N. Zidar7Fig. 7.11. Paraganglioma. a Characteristic arrangement into“Zellballen” composed of central chief and peripheral sustentacabular cells. b Chief cells stain immunohistochemically for synaptophysincells typically have an eosinophilic, finely granular cytoplasmand central vesicular nuclei. Cellular pleomorphismmay be present and is occasionally prominent,but prognostically unimportant. Rare mitoses can befound, usually less than 2–3 per 10 high power fields.The supporting cells are usually inconspicuous, spindleshaped,and most frequently found at the edge of the cellballs [18, 375].Immunohistochemical findings are characteristicand decisive for the diagnosis. The chief cells are positivefor neuroendocrine markers, such as chromogranin,synaptophysin and neuron-specific enolase (Fig. 7.11b) .The paragangliomas usually stain negatively for epithelialmarkers, such as cytokeratin, epithelial membraneantigen, carcinoembryonic antigen, and calcitonin.Sustentacular cells are positively stained with S-100protein and glial fibrillary acid protein [18, 375].Laryngeal paragangliomas must be primarily differentiatedfrom typical and atypical carcinoids. The mostreliable aid is positivity for both epithelial (cytokeratin,epithelial membrane antigen and carcinoembryonic antigen)and neuroendocrine markers in both types of carcinoids[107, 110]. Other, more remote differential diagnosticpossibilities include malignant melanoma, renalcell carcinoma and medullary thyroid carcinoma. Melanomacan be confirmed by melan A and HMB-45 positivity.Renal cell carcinoma, in contrast to paraganglioma,does not express neuroendocrine markers. Medullarycarcinoma expresses positive staining for calcitonin,amyloid and CEA [18, 106, 375].Since paragangliomas are only exceptionally malignant,conservative surgical treatment is suggested [18,20, 110]. There are no histological criteria that could reliablypredict the biological behaviour of the lesion [18].In a recent genetic study, it was postulated that sporadichead and neck paragangliomas have deletions at thesame or closely related loci (11q13 and 11q22-23) as theirfamily counterparts [33].7.6.5 Granular Cell TumourICD-O:9580/0Granular cell tumour (GCT) is an uncommon benign,slowly growing lesion and about half of the cases occurin the head and neck region [201, 205, 371]. Varioushistogenetic origins have been attributed to GCT,but recent prevailing opinion supports a relationshipto Schwann cells. The tongue and subcutaneous tissueof the head and neck are the most common sites of thetumour, while laryngeal involvement is less frequent[162, 176, 187, 205, 286, 330, 371], and comprises about10% of all cases [205]. These tumours most commonlyappear in the posterior area of the true vocal cords andhalf of them extend into the subglottis as a smooth,polypoid and sessile lesion [205, 286, 371]. GCT typicallyappears between the fourth and fifth decades andthe average age for laryngeal forms is 36 years [286].The tumour rarely occurs in children [162]. Hoarseness,stridor and dysphagia are the most common complaints.Histologically, the tumour is poorly circumscribedand consists of clusters and sheets of rounded and polygonalcells with indistinct cellular borders and small,bland-looking and central nuclei. A mild degree of nuclearpleomorphism may be present, but mitotic activityis low. Cytoplasm of tumourous cells is abundant,characteristically coarsely granular and eosinophilic.