Midline malignant reticulosis.

A combined histological, ultrastructural and cytological study was performed on biopsy materials from nasal lesions of 2 patients with midline granuloma. The histological and ultrastructural features of the tissues were necrosis, inflammation and infiltration of atypical histiocytic cells. The DNA-content of these histiocytes exceeded the limits of the 5c Exceeding-Rate and the 2c Deviation Index. The morphological characteristics and the results of the DNA-cytophotometry classify the midline granuloma as a local malignant histiocytosis. Clinical follow-up of the cases suggests that radiation therapy offers a good prospect of treatment success.