The diagnosis and management of T-natural killer cell lymphoma of the sinonasal tract

Non-Hodgkin's lymphoma (NHL) of the sinonasal tract is a relatively uncommon neoplasm that can be morphologically difficult to distinguish from nonneoplastic diseases. The lethal midline granuloma syndrome was formerly believed to encompass a broad spectrum of diseases, including Wegener's granulomatosis, polymorphic reticulosis, idiopathic midline destructive disease, and non-Hodgkin's lymphoma. The lack of definitive histopathologic differentiation of this group of lesions provided little guidance in their management. However, recent advancements in immunocytochemical phenotyping and molecular genetics have led to a revision of this outdated classification. Except for Wegener's granulomatosis, a well-characterized autoimmune disease, the majority of these lesions are now known to represent lymphomas of either B- or T-cell origin. T-cell or natural killer-cell phenotype (T-NK) lymphoma constitutes a particularly aggressive form of sinonasal lesions and carries a poor prognosis.