Non-contiguous Meningeal Recurrence of Olfactory Neuroblastoma: A Case Report and Literature Review.

Olfactory neuroblastoma is an uncommon malignant tumor of neural crest origin arising from the olfactory epithelium of the superior nasal cavity. There are some reports of local recurrence or continuous extension along the olfactory epithelium to the central nervous system, but non-contiguous distant meningeal metastasis without local recurrence at the primary site is rare. We report a case of non-contiguous meningeal recurrence of olfactory neuroblastoma presenting as a giant frontal mass. A 66-year-old woman was admitted with a left nasal intranasal localized tumor without cranial extension and gross total removal was achieved. Pathological examination showed olfactory neuroblastoma and radiation therapy was added in a limited region of the removal cavity. Radiological follow-up continued for 10 years and there was no local recurrence. Sixteen years after radiation therapy, the patient found a slight frontal mass gradually growing. Magnetic resonance imaging revealed an enhanced mass lesion of 7 cm in thickness and 9 cm in diameter associated with marked thickness of the frontal bone, intradural cystic mass compressing the bilateral frontal lobe, and no local recurrence. A second operation was performed followed by radiotherapy and we diagnosed no-contiguous meningeal recurrence of metastatic olfactory neuroblastoma. Olfactory neuroblastoma is a locally aggressive tumor. Although metastasis of this tumor has been reported, non-contiguous spread to the dura is rare. Understanding the route of remote metastasis and careful evaluation after primary treatment are needed to avoid misdiagnosis and treatment delays.