J Korean Assoc Oral Maxillofac Surg.  2023 Aug;49(4):233-238. 10.5125/jkaoms.2023.49.4.233.

A rare histopathological variant of Schwannoma with rosette-like arrangements and epithelioid cells: a case report from a histopathologist’s perspective

• Mehendiratta M
• Sant VK
• Lakhanpal M
• Chauhan K

• KMID: 2545591
• DOI: http://doi.org/10.5125/jkaoms.2023.49.4.233

Abstract

Schwannomas exhibit histopathological variation that leads to diagnostic dilemmas, although less frequent in the oral cavity. We describe a case with unique histopathology and no relevant clinical history that adds to the breadth of literature on the diversity presented by Schwannoma. A 60-year-old female patient presented with a small dome-shaped, asymptomatic swelling on the alveolar ridge 6 years in duration. Histopathologically, it showed rich cellular pathology with a unique arrangement of tumor cells forming irregular rosettes. Each rosette presented with a central core of fibrincollagenous material and the tumor cells were arranged on the periphery, exhibiting epithelioid change with evidence of mild cellular and nuclear pleomorphism. On immunohistochemical evaluation, the cells were strongly and diffusely positive for S-100 and negative for Ki-67. A diagnosis of benign Schwannoma with a rosette-like arrangement with epithelioid change was made. The case report emphasizes the risk of misdiagnosis and the importance of awareness regarding rare histopathological variants of Schwannoma.

Keyword

Epithelioid cells; Verocay bodies; Neurilemmoma; Collagen; Rosette

Figure

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  Fig. 1 A small dome-shaped, well-defined swelling of the left mandibular alveolar ridge.

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  Fig. 2 Multiple rosette-like arrangements of tumor cells with fibro-collagenous cores surrounded by fascicles of spindle-shaped tumor cells (H&E staining, ×10).

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  Fig. 3 A single rosette with epithelioid cells encircling the rosette-like radiating fibro-collagenous cores with mild amount of atypia. The tumor cells on the left side are spindle-shaped resembling typical Schwann cells (H&E staining, ×40).

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  Fig. 4 The blue-colored center of rosettes and the periphery of the tumor confirm the presence of collagen fibers (MT staining, ×4).

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  Fig. 5 The brown-colored diffuse deposition of S-100 immuno-marker suggests Schwann cell origin of tumor (S-100 staining, ×10).

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  Fig. 6 Absence of Ki-67 immuno-marker is suggestive of low proliferation index confirming the absence of malignancy (Ki-67 staining, ×40).

Reference

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