Cellular Schwannoma of the Paranasal Sinuses: Initial Report of a Case

Abstract

Cellula r schwannomas are a benign variant of classic schwannomas. Their histologic appearance closely mimics that of malignant periph eral nerve-sheath tumors, which are high-grade sarcomas. In this article, we describe what to our knowledge is the fi rst reported case of a cellular schwannoma ofthe paranasal sinuses and only the 33'dreported case of any schwannoma at this site. We also discuss the histology and management of cellular schwannomas and review the pertinent literature.

Atypical Presentation of Sinonasal Cellular Schwannoma: A Nonsolitary Mass with Osseous, Orbital, and Intracranial Invasion

“…Head and neck schwannomas rarely occur in the sinonasal cavities, and they are typically described as solitary encapsulated lesions confined to the nasoethmoid region. [1][2][3][4][5][13][14][15][16][17] The less common cellular schwannoma has been described in the sinonasal tract, and the lack of encapsulation along with bony erosion of this variant was previously noted. 11,16 Although schwannomas are uncommon in this location, and cellular schwannomas even more so, the recognition of this entity in this anatomical site is important.…”

“…[1][2][3][4][5][13][14][15][16][17] The less common cellular schwannoma has been described in the sinonasal tract, and the lack of encapsulation along with bony erosion of this variant was previously noted. 11,16 Although schwannomas are uncommon in this location, and cellular schwannomas even more so, the recognition of this entity in this anatomical site is important. [1][2][3][4][5][13][14][15][16][17] The reported case reiterates the potential risk of rendering a malignant diagnosis on biopsy, particularly in light of the aggressive radiographic findings.…”

“…11,16 Although schwannomas are uncommon in this location, and cellular schwannomas even more so, the recognition of this entity in this anatomical site is important. [1][2][3][4][5][13][14][15][16][17] The reported case reiterates the potential risk of rendering a malignant diagnosis on biopsy, particularly in light of the aggressive radiographic findings. Although bone erosion is well described in cellular schwannomas at a variety of anatomical locations, it appears that those arising in this anatomical site tend to have the additional aggressive feature of being nonencapsulated with an infiltrative growth pattern.…”

“…The distinction between conventional schwannomas versus cellular schwannomas, which may have malignant clinical features, is more clearly distinguished in the pathology literature. For instance, cellular schwannoma involving the paranasal sinuses was actually first described in the publication by Hasegawa et al and not by al-Otieschan et al 11,16 Given the difference in clinical behavior between these two pathologies, close collaboration with a pathologist would be helpful for correctly reporting cases of schwannoma in the future.…”

Schwannoma of the inferior turbinate: case report and review of literature

“…Degenerative changes such as cyst formation are not uncommon in schwannomas (5) . Rarely, the tumour can become very cellular and mistakenly diagnosed as a malignant schwannoma (6) ; however, malignant degeneration is exceedingly uncommon. Features that distinguish a schwannoma from a neurofibroma include a neurofibroma's lack of a capsule and proliferation of all the elements of a peripheral nerve, such as the axons, Schwann cells, fibroblasts and perineural cells (7) .…”