Recurrent Olfactory Neuroblastoma in Remote Leptomeninges, Mimicking Intracranial Meningioma.

BACKGROUND: Olfactory neuroblastoma (ONB) is an uncommon neoplasm that arises from olfactory epithelium in the nasal cavity near the cribriform plate. Although local recurrence or direct extension along olfactory epithelium and metastasis to the central nervous system has been reported, remote leptomeningeal metastasis is quite rare. In our report of a leptomeningeal metastasis of ONB without recurrence of primary site, we discuss the possible pathogenesis of this rare phenomenon with a review of the literature.

CASE DESCRIPTION: A 56-year-old woman was admitted with epistaxis. Magnetic resonance imaging revealed a mass in the right cribriform plate and ethmoid sinus with intracranial extension. She was primarily treated with craniofacial resection followed by radiotherapy. Gross total resection was achieved, but annual follow-up magnetic resonance imaging showed a new enhancing mass in the left parietal meninges mimicking meningioma without local recurrence at 5 years after the first operation. A second operation was performed, and pathologic examination confirmed the lesion as metastatic olfactory neuroblastoma.

CONCLUSIONS: ONB is a locally aggressive tumor, but it also potentially spreads to remote leptomeninges via blood or cerebrospinal fluid. Therefore, careful evaluation is needed not to misdiagnose a meningioma and delay the treatment. Moreover, understanding the route of remote leptomeningeal metastasis and en-bloc resection of tumor at first operation might reduce leptomeningeal metastasis, irrespective of surgical corridors.