Olfactory neuroepithelioma arising from the olfactory placode.

The patient was a 54-year-old man, who had lost his sense of smell 6 years previously and had started to become forgetful about 6 months prior to presenting at hospital. MRI admission showed a large multicystic tumor with Gd-DTPA enhancement extending from the anterior cranial fossa through the sphenoid sinus and into the nasal cavity. Histopathological examination revealed extensive proliferation of small round cells that were divided by connective tissue septae. The tumor cells occasionally formed tubular structures, although no basement membranes were present. On immunostaining, round tumor cells were positive for neuron-specific enolase, synaptophysin, and chromogranin A, while cells forming tubules were positive for AE 1 and CAM 5.2. Almost all of the tumor cells were positive for Ber-EP4, and some of the epithelioid cells surrounding the tubular structures were also positive for luteinizing hormone-releasing hormone (LH-RH). Electron microscopy demonstrated sporadic intercellular junctions, many microtubules in the tumor cell processes, and clear- and dense-cored vesicles in the cytoplasm. Based on the results, this case appears to be the first documented neuroepithelioma with Ber-EP4- and LH-RH-positive cells arising from the olfactory placode.