Midline "nonhealing" granuloma.

Destructive processes of the midface can occur in a wide variety of diseases. Intrinsic in consideration of these is a cluster of lesions, including Wegener's granulomatosis (WG), idiopathic midline granuloma (IMG), polymorphic reticulosis (PR), and lymphoma. Although there is still confusion as to whether the latter three represent a spectrum of the same malignant process, there is general agreement that WG is a separate entity on the basis of clinical presentation and therapeutic response. It is probable that PR is an emergent lymphoma, with the same prognostic and therapeutic features. Idiopathic midline granuloma is clinically similar to PR and lymphoma, but histologically it appears to be inflammatory in nature with no clearly definable malignant cell type present. At this point in time three diseases are best collectively referred to as midline "nonhealing" granuloma. The cases presented represent the spectrum of this enigmatic process.