Pathology of the Head and Neck

Nasal Cavity and Paranasal Sinuses Chapter 2 61Fig. 2.15. Tubulopapillary carcinoma: low-grade proliferation ofcuboidal to columnar epithelial cells forming tubules at the centreand papillae at the surfaceafrom metastatic renal cell carcinoma [31, 280]. A tubulopapillaryvariant has recently been reported (Fig. 2.15)[234] that has to be differentiated from terminal tubulusadenocarcinoma of the nasal seromucous glands [139].2.11.10.2 Salivary-Type Low-GradeAdenocarcinomasMucoepidermoid carcinoma, polymorphous low-gradeadenocarcinoma (Fig. 2.16) and acinic cell carcinomaoriginate only on rare occasions from the seromucousglands of the sinonasal mucosa [43, 110, 150, 190, 200,239]. Most mucoepidermoid carcinomas of the sinonasaltract are low-grade. Some large oncocytic tumoursof the sinonasal tract may behave in a locally aggressivefashion and are better classified as low-grade adenocarcinomas[55, 103, 110]. All these tumours are dealt within detail in Chap. 5 on salivary glands. Their main differentialdiagnoses are other salivary- or non-salivarytypelow-grade adenocarcinomas.2.11.11 Sinonasal Malignant LymphomasMalignant lymphomas of the sinonasal region compriseapproximately 6% of all sinonasal malignancies [134]. Inour Barcelona series, they account for 9.5% (Table 2.1).In western countries, about 50% of sinonasal lymphomasare of B-cell type, whereas the other 50% mostly showedNK/T-cell lineage [38]; nevertheless, other reports pointto more variable rates [3, 72, 77, 85]. Conversely, in orientalpopulations most primary lymphomas of the nasalcavity and nasopharynx are of NK/T cell lineage [49, 50,52, 92, 233].Sinonasal B-cell lymphomas are in general composedof a diffuse proliferation of large lymphoid cells, or of abFig. 2.16. Polymorphous low-grade adenocarcinoma. a CT scanshowing an irregularly nodular lesion destroying the anterior nasalseptum. Courtesy of Prof. J. Traserra, Barcelona, Spain. b Variegatedglandular arrangements composed of tubules with blandcellularity are seen beneath respiratory epitheliumdiffuse mixed pattern of small and large cells. They infiltrateand expand the subepithelial soft tissue and mayextend into the underlying bone. Sinonasal B-cell lymphomaslack epitheliotropism, polymorphous cell infiltrate,angiocentricity, prominent necrosis, and fibrosis.They are usually positive for B-cell markers (CD20and CD79a) and negative for NK/T cell markers. lightchain restriction is seen more often than restriction.They are often negative for EBV markers. Radiotherapyand chemotherapy is the standard treatment for advancedtumours [213].Sinonasal NK/T cell lymphomas were labelled in pastdecades with terms such as “lethal midline granuloma”,“polymorphic reticulosis” and “angiocentric T-cell lymphoma”,among others. Until quite recently, non-B cellsinonasal lymphomas were considered as other forms ofT-cell lymphoma, frequently displaying angiocentricity.Patients may present either with an obstructive massor with mid-facial destructive lesions. Histologically, anangiocentric and angiodestructive infiltrate with extensivenecrosis (Fig. 2.17a) is frequently seen. In NK/T-celllymphoma, cells may be small, medium-sized, large, oranaplastic, and may show a conspicuous admixture of