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 pres enting at hospital. MRI admission showed a large multicystic tumor with Gd- DTPA enhancement extending from the anterior cranial fossa through the sphe noid sinus and into the nasal cavity. Histopathological examination reveale d extensive proliferation of small round cells that were divided by connect ive tissue septae. The tumor cells occasionally formed tubular structures, although no base ment membranes were present. On immunostaining, round tumo r cells were positive for neuron-specific enolase, synaptophysin, and chrom ogranin 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 ep ithelioid cells surrounding the tubular structures were also positive for l uteinizing hormone-releasing hormone (LH-RH). Electron microscopy demonstra ted sporadic intercellular junctions, many microtubules in the tumor cell p rocesses, and clear- and dense-cored vesicles in the cytoplasm. Based on th e results, this case appears to be the first documented neuroepithelioma wi th Ber-EP4- and LH-RH-positive cells arising from the olfactory placode.