<p class="abstract"><span lang="EN-US">A granular cell tumor (GCT) is a rare neoplasm. It grows slowly, presumably originates from a Schwann cell, and is typically benign. Histopathologically, GCTs are composed of loosely infiltrating sheets of large, pale, polyhedral cells with abundant granular eosinophilic cytoplasm and a pale, centrally situated nucleus. Immunohistochemically, GCTs express the S-100 protein and neuron-specific enolase. A GCT can occur anywhere in the body. Half of all GCTs

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... ccur in the head and neck regions, especially on the tongue, but they are rarely found in the nasal cavity. A GCT usually arises as a solitary tumor and can be confirmed only by a histologic examination. The appropriate treatment is excision of the lesion. </span>Here, we present a rare case of a GCT originating in the right posterior ethmoid sinus in the nasal cavity. A GCT originating in a posterior ethmoid sinus has not been reported thus far. In our case, a simple nasal polyp was found in the left ethmoid sinus of the patient. Thus, we initially misjudged the GCT in the right nasal cavity as a simple nasal polyp.</p>