Question: A 31 year old male is evaluated for a sinonasal tumor. His symptoms prior to presentation included unilateral proptosis, loss of sense of smell, and intermittent epistaxis. The tumor is biopsied and the pathologist notes small round blue cells in most of the biopsy specimen. Stains are requested and the tumor is positive for S100 and SOX10 but is negative for neuron specific enolase. What is the most likely diagnosis?

a) Mucosal melanoma

b) Inverted papilloma

c) Schwannoma

d) Esthesioneuroblastoma

[Answer will be posted with next week's new question]

Answer to last week's question, “Making The Grade" (April 1, 2019)

C - Grade 3.