Primitive round cell neoplasms are difficult to distinguish from one another without ancillary techniques. Many tumors such as lymphoma, melanoma, sinonasal undifferentiated carcinoma, neuroendocrine carcinoma mimic olfactory neuroblastoma leading to misdiagnosis 1. This causes wrong treatment regimen and poor prognosis for certain treatable tumors.

We discuss in this report of case of orbit/ paranasal sinus tumor diagnosed as olfactory neuroblastoma, turned out to be Rhabdomyosarcoma with neuroendocrine differentiation. And also discuss the importance of immunohistochemistry in diagnosing such cases.