Central neurofibromas in two dogs.

Two dogs each had a fibrous tumor of the central nervous system. One tumor involved the spinal cord and ventral nerve root, and the other involved the midbrain and posterior brain stem. Both tumors had spindle-shaped cells arranged in rhythmic patterns. There was perivascular tumor cell infiltration in the adjacent parenchyma. The tumor cells strongly resembled fibroblasts and seemed to produce collagen. Because both tumors were near nerve roots and because their histological appearances were characteristic of nerve sheath tumors they were classified as central neurofibromas.