Lethal midline granuloma with a novel T-cell phenotype as found in peripheral T-cell lymphoma.

Lethal midline granuloma (LMG), initially a clinical description, includes an uncommon group of disorders characterized by a relentless, destructive process involving the upper respiratory structures. Its etiology and pathogenesis are uncertain, probably varied, and the distinction between inflammatory and malignant processes is difficult despite extensive clinical and histopathologic evaluation. The need for new techniques for rapid diagnosis has important therapeutic implications. Using an extensive panel of T- and B-cell monoclonal antibodies the authors describe a patient with clinically and pathologically typical LMG demonstrating an "activated" T-cell phenotype with a "novel" pattern characteristic of peripheral T-cell lymphoma, strongly implying that some cases of LMG are more closely related to neoplastic T-cell lymphoproliferative disorders than to inflammatory conditions. Further studies using these immunotyping techniques may help clarify the pathogenesis of LMG, and may uncover specific diagnostic and prognostic phenotypic patterns.