The authors report a case of intracranial meningioma with granulofilamentous inclusions. A 50-year-old man had right trigeminal neuralgia due to trigeminal nerve compression by a petroclival tumor and received tumor resection. Microscopically, tumor cells containing eccentric nuclei and intracytoplasmic hyaline inclusions were arranged in sheets and whorls. The inclusions were negative for periodic acid-Schiff reaction. No histological anaplasia was seen. Immunohistochemistry showed epithelial membrane antigen reactivity on the cytoplasmic membrane. Immunoreactivity for vimentin was recognized in cytoplasm adjacent to inclusions. However, confocal laser microscopic study revealed immunoreactivity for vimentin even inside some inclusions. Ultrastructurally, interdigitation of cytoplasmic processes and desmosomes connecting adjacent cells were noted. Inclusions were composed of numerous fine osmiophilic granules attached by intermediates filaments. These findings were consistent with a meningioma with the granulofilamentous inclusions described earlier. The findings demonstrated by confocal laser microscopy and electron microscopy suggest that these granular materials may be the metabolic products of vimentin filaments.

This report concerns a 66-year-old man with a melanocytoma arising at the foramen magnum. Magnetic resonance imaging disclosed a well-circumscribed tumor extending from the medulla oblongata to C1 with gadolinium enhancement. A heavily pigmented tumor located under the leptomeninges was removed surgically. Although the patient died 8 months later of renal cell carcinoma, no recurrence or metastasis of the melanocytoma was detected by radiographic examination. Microscopically, the resected tumor was composed of polygonal to spindle-shaped cells containing large amounts of melanin. The bland nuclei of the tumor cells were of uniform size. No mitotic figures were seen. The tumor cells were positively immunostained for S-100 protein and by antibody HMB-45. They were not stained using the Ki-67 (MIB-1) antibody, indicating low proliferative activity. The ultrastructural examination revealed numerous mature melanosomes and basal laminae surrounding nests of cells. The tumor was diagnosed as a melanocytoma on the bases of its microscopic features and the lack of Ki-67 immunoreactivity. The ultrastructural and immunohistochemical features of melanocytomas are distinct from those of meningiomas. It is likely that melanocytomas and melanotic schwannomas represent opposite extremes of the continuous spectrum of neuroectodermal tumors derived from the neural crest.

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