Answer: Glomus tumor

Histology: The tumor cells form irregular nests within the submucosa that form collars around thin vascular channels. The cells have round to oval uniform nuclei and eosinophilic cytoplasm. The cells lack significant pleomorphism or mitotic activity, and there is no tumor necrosis. An actin immunohistochemical stain is shown.

Discussion: Nasal glomus tumor is an example of a common and well-recognized entity occurring in an unusual and unexpected anatomic site. Although in other sites the term “glomangioma” is used to designate a specific variant of glomus tumor, in the nasal cavity these terms are used interchangeably. Indeed, use of the term “glomangioma” is very convenient when dealing with these head and neck tumors because it minimizes confusion with certain paragangliomas of the head and neck – i.e. glomus jugulare and glomus tympanicum.

Confusion with paraganglioma may extend beyond these semantic issues. They also share some morphologic features including a prominent vascular component and an organoid growth pattern. Immunohistochemistry is useful. Glomus tumors lack immunohistochemical staining for neuroendocrine markers such as chromogranin. Instead, they are consistently immunoreactive for actin reflecting their myogenic differentiation. The organoid pattern of growth, epithelioid appearance of the tumor cells, and strong actin staining would be uncharacteristic of hemangiopericytoma.

Like their soft tissue counterparts, glomus tumors of the nasal cavity are benign. Simple excision is generally curative.