Malignant lymphomas of the sinonasal region comprise approximately 6% of all sinonasal malignancies . In our Barcelona series, they account for 9.5% (Table 2.1). In western countries, about 50% of sinonasal lymphomas are of B-cell type, whereas the other 50% mostly showed NK/T-cell lineage ; nevertheless, other reports point to more variable rates [3, 72, 77, 85]. Conversely, in oriental populations most primary lymphomas of the nasal cavity and nasopharynx are of NK/T cell lineage [49, 50, 52, 92, 233].
Sinonasal B-cell lymphomas are in general composed of a diffuse proliferation of large lymphoid cells, or of a
Fig. 2.16. Polymorphous low-grade adenocarcinoma. a CT scan showing an irregularly nodular lesion destroying the anterior nasal septum. Courtesy of Prof. J. Traserra, Barcelona, Spain. b Variegated glandular arrangements composed of tubules with bland cellularity are seen beneath respiratory epithelium
Fig. 2.16. Polymorphous low-grade adenocarcinoma. a CT scan showing an irregularly nodular lesion destroying the anterior nasal septum. Courtesy of Prof. J. Traserra, Barcelona, Spain. b Variegated glandular arrangements composed of tubules with bland cellularity are seen beneath respiratory epithelium diffuse mixed pattern of small and large cells. They infiltrate and expand the subepithelial soft tissue and may extend into the underlying bone. Sinonasal B-cell lymphomas lack epitheliotropism, polymorphous cell infiltrate, angiocentricity, prominent necrosis, and fibrosis. They are usually positive for B-cell markers (CD20 and CD79a) and negative for NK/T cell markers. k light chain restriction is seen more often than X restriction. They are often negative for EBV markers. Radiotherapy and chemotherapy is the standard treatment for advanced tumours .
Sinonasal NK/T cell lymphomas were labelled in past decades with terms such as "lethal midline granuloma", "polymorphic reticulosis" and "angiocentric T-cell lymphoma", among others. Until quite recently, non-B cell sinonasal lymphomas were considered as other forms of T-cell lymphoma, frequently displaying angiocentricity. Patients may present either with an obstructive mass or with mid-facial destructive lesions. Histologically, an angiocentric and angiodestructive infiltrate with extensive necrosis (Fig. 2.17a) is frequently seen. In NK/T-cell lymphoma, cells may be small, medium-sized, large, or anaplastic, and may show a conspicuous admixture of
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