Expression patterns of Trk-A, Trk-B, GRP78, and p75NRT in olfactory neuroblastoma

Olfactory neuroblastoma is an uncommon neuroectodermal tumor of the sinonasal tract. It represents 2% to 3% of sinonasal neoplasms. Most olfactory neuroblastoma behave locally aggressive with 30% recurrence rates. A subset metastasizes to lymph nodes and/or distant sites. Grading of olfactory neuroblastoma involves a combination of factors with low-grade tumors having better survival than high-grade tumors. The grade does not always predict prognosis, however, as metastases can be seen in all grades of olfactory neuroblastoma. Trk-A, Trk-B, and p75NRT are neurotrophin receptors associated with numerous solid malignancies, particularly pediatric neuroblastoma. GRP78 is an endoplasmic reticulum protein, associated with differentiation of neuroblastic cells. Trk-A, p75NRT, and GRP78 overexpression are favorable prognostic factors in pediatric neuroblastoma, whereas Trk-B is associated with a poorer prognosis in these tumors. Olfactory neuroblastoma is clinically distinct from pediatric neuroblastoma but shares some histological features. Trk-A and p75NRT have been demonstrated in olfactory neuroblastoma previously. Trk-B and GRP78 have not been investigated in olfactory neuroblastoma. None of these markers have been correlated with grade or outcome in olfactory neuroblastoma. To investigate the role of Trk-A, Trk-B, p75NRT, and GRP78, a series of 20 olfactory neuroblastomas was stained with these antibodies. Trk-A and Trk-B stained most cases of olfactory neuroblastoma (90% and 85%). GRP78 stained most cases (90%), although weakly. P75NRT demonstrated focal membranous staining in a sustentacular pattern (60%). None of these markers correlated with Hyams grade. None of these markers definitively correlated with patient outcome. Neurotrophin receptors do not appear to have a prognostic role; however, Trk's may play an oncogenic role in olfactory neuroblastoma.