MICROSCOPIC DESCRIPTION: The section shows polypoid nasal mucosa in each of the two specimens. The lamin apropria is expanded by a desnely hypercellular tumour. This is a composed of cells with uniform small round and oval hyperchromatic nuclei and minimal cytoplasm. These are arranged in irregularly shaped solid aggregates within a loose fibrous stroma. Frequent mitotic and apoptotic figures are identified.
Immunohistochemistry shows staining of tumour cells for c-kit, bcl-2, INI-1, BerEp4, CD56 and p16. There is patchy perinuclear dot immunostaining for epithelial membrane antigen (EMA). The following immunostains are negative - MIC2 (CD99), p40, EMA, PgR, TTF-1, chromogranin, neurone specific enolase, pancytokeratin AE1/AE3, synaptophysin, beta-tubulin, CD138, S-100 protein, CD20 and CAM 5.2. There is no light chain restriction.
FINAL DIAGNOSIS: Undifferentiated tumour with features most consistent with esthesioneuroblastoma.