Melanin macroglobules as a cellular marker of neurofibromatosis: a quantitative study.

To investigate the usefulness of melanin macroglobules (MMG) as a cellular marker for neurofibromatosis, their density was quantified in biopsies of café-au-lait spots (macules) (CALM) from 22 patients with von Recklinghausen's neurofibromatosis, 6 patients with bilateral acoustic neurofibromatosis, and 19 controls. The density of MMG was significantly higher in biopsies of the CALM of patients with von Recklinghausen's neurofibromatosis than in patients with bilateral acoustic neurofibromatosis (p less than .01) or controls (p less than .0008). The mode of acquisition of von Recklinghausen's neurofibromatosis (inherited vs new mutation) was not related to the density of MMG. On light microscopy, 14/22 (64%) patients with von Recklinghausen's neurofibromatosis had 11 or more MMG per 5 high-power fields. In contrast, none of the other two groups had more than 10 MMG per 5 high-power fields.