Advances in immunocytochemical phenotyping and molecular genetics have nearly resolved the histopathologic and therapeutic quandaries brought about by a diagnostic nomenclature that provided little guidance in the management of midfacial necrotizing lesions. Gone are terms like midline granuloma syndrome, lethal midline granuloma, polymorphic reticulosis, lymphomatoid granulomatosis, midline destructive granuloma, and idiopathic midline destructive disease. They have been replaced by the appreciation that the majority of the lesions are lymphomas of the sinonasal tract. The lymphomas are of B- or T-cell lineage and have a broad biologic spectrum from low to high grade. Still to be addressed are apparent geographic differences in biologic behavior, the epidemiologic significance of a preponderance of T-cell nasal lymphomas in the Orient, and optimum therapeutic regimens.