Esthesioneuroblastoma (olfactory neuroblastoma)

General: Rare (on the order of 300 reported cases as of 1994) malignancy of the nasal vault, believed to arise from olfactory epithelium, and which has highly variable biologic activity (from indolent growth over decades to rapid progression, metastasis, and death within months). It has a bimodal age distribution (teens and 60's) and is most common in Caucasians, but has been reported in many races.

Gross:

Microscopic: Composed of small, round to oval blue cells arranged in rosette or pseudorosette patterns with radially oriented nuclei, separated by fibrous septa. The surrounding stroma is composed of undifferentiated nuclei and neurofibrillary cords, with marked microvascularity and perivascular palisading. Mitotic figures are rare, and calcification and necrosis are sometimes seen.

Differential Diagnosis:

• lymphoma
• Ewings sarcoma / PNET
• plasmacytoma
• rhabdomyosarcoma
• small cell carcinoma

Stains:

• Positive: CKC+, NSE+ (strong), synaptophysin+ (strong), chromogranin+, neurofilament+, occasional GFAP+, catecholamines, S100+ in cells at periphery of cell nests
• Negative: EWS-FL1-, CD99-, EMA-, desmin-
• Suggested, focused panel:

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