Fine needle aspiration cytology of primary sphenoid sinus esthesioneuroblastoma metastatic to the skin.

Esthesioneuroblastoma (ENB) is a rare tumor derived from olfactory neuroepithelium. ENB in a site outside of where olfactory epithelium exists is exceedingly rare with only five cases of ENB isolated to the sphenoid sinuses described in the literature to date. To the best of our knowledge, a skin metastasis of ENB outside the head and neck region has not been reported. We present an unusual case of a 33-year-old male diagnosed with primary sphenoid sinus ENB, who underwent surgical resection of the tumor followed by chemoradiation. About 5 months later, the patient developed a dermal mass in the sternal region, clinically suspicious for metastasis. Fine needle aspiration (FNA) revealed a tumor with morphological features and immunophenotype consistent with the metastasis from patient's known primary sphenoid sinus ENB. Our case demonstrates that the skin may be a rare site of a metastatic ENB, and FNA is a cost-effective and reliable diagnostic method of a suspected cutaneous metastasis.