Midline granuloma includes diverse clinicopathological entities, such as Wegener granulomatosis, polymorphic reticulosis, lethal midline granuloma and conventional malignant lymphoma of the nose usually of B-cell origin. The authors describe five patients with LMG clinically and pathologically typical. Using an extensive panel of monoclonal antibodies, they demonstrate an "activate" T-cell phenotype observed on the initial lesion of the face in one patient, similar to that found in two patients with LMG but studied after dissemination in peripheral T-cell lymphoma. Furthermore, many atypical cells were found in LMG, and stained with the Ki-67 monoclonal antibody, a marker of proliferating cells. These findings support the view that LMG is closely related to T-cell malignancies. Two of them were treated with recombinant Interferon alpha 2a followed by a response rapidly objective. Immunohistologic studies are very important for confirming the T-cell origin of such a disease and for selecting patients to be treated with Interferon alpha.