Objectives: Chordomas are rare malignant tumors with a broad differential diagnosis, including chondrosarcomas and metastatic carcinomas. Recently, insulinoma-associated protein 1 (INSM1) has gained great interest regarding the diagnosis of neuroendocrine tumors but also extraskeletal myxoid chondrosarcomas. However, its expression in chordomas remains largely unknown.
Methods: We retrospectively examined 57 chordomas for INSM1 expression.
Results: INSM1 expression was found in only 5% of tumors.
Conclusions: This marker is rarely expressed in this type of tumor, raising questions about neuroendocrine differentiation.
Keywords: Chondrosarcoma; Chordoma; Differential diagnosis; Immunohistochemistry; Neuroendocrine.
© American Society for Clinical Pathology, 2021. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.