[On classification of changes in necrotizing lesions of the midface].

Lethal midline granuloma syndrome (LMG) describes lesions of the midface and is characterized by a progressive and often fatal ulceration and destruction of the upper air way involving the nose, the paranasal sinuses, the palate and the soft tissues of the face. Under the term LMG we distinguish four entities: idiopathic midline destructive disease (IMDD), polymorphic reticulosis (PR), non Hodkin's lymphoma and Wegener's granulomatosis (WG). Review of the literature allows to present the differential diagnosis making use of latest technological achievements in clinical immunology and immunohistochemistry. First of all the LMG must be discriminated from localized WG occurring in the midface. The clinical, serological and histopathological findings in WG are described. Literature review is carried out and recent concepts of it's etiology and pathogenesis are presented. Autoantibodies directed against cytoplasmic antigens of neutrophils (ANCA) with specificity for proteinase 3 (PR 3) are valuable marker for differential diagnosis and specificity are discussed. We make a comparison between the "limited" or "non renal" WG and "classical" or "renal" form of the disease.