extranodal head and neck lymphomas in guatemala: high frequency of epstein-barr virus-associated sinonasal lymphomas. | sinonasal lymphomas of t cell or natural killer cell (t/nk cell) phenotype represent a subset of extranodal head and neck lymphomas. t/nk cell sinonasal lymphomas have been described in diverse geographic settings, including china, japan, peru, northern europe, and north america. the frequency of these lymphomas is highly dependent on the geographic location in which they occur, their incidence being low in europe and north america and relatively high in asian countries and in peru. regardless o ... | 1997 | 9224753 |