Olfactory ensheathing cell tumor with neurofibroma-like features: a case report and review of the literature.

A 32-year-old man had seizure attack since April 2008 and radiographic examination revealed a heterogeneous enhancing mass at the left subfrontal region. He underwent craniotomy for tumor removal on October 1, 2008. The tumor, which was grayish white with glistening appearance and rubbery consistency, was traced to the proximal part of left olfactory tract. Histopathological examination revealed a hypocellular tumor with dense hyalinization in most areas. The tumor cells had ovoid to elongate and often comma-shaped nucleus. Myxoid change of the stroma was apparent in places. Most of the tumor cells were immuno-reactive for S-100 protein. Staining for Leu 7 (CD57 or HNK-1) was negative. Bodian method illustrated many axons within the tumor. Ultrastructural study of the tumor cells showed features compatible with those of olfactory ensheathing cell. The tumor was designated as olfactory ensheathing cell tumor with neurofibroma-like features. There have been 14 nerve sheath tumors arising from the olfactory nerve reported in the literature; all of them had the morphology of schwannoma. Our case, which had the morphology simulating neurofibroma was the first of its kind to be recorded.