INSM1 Expression in Chordomas

Abstract

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. We retrospectively examined 57 chordomas for INSM1 expression. INSM1 expression was found in only 5% of tumors. This marker is rarely expressed in this type of tumor, raising questions about neuroendocrine differentiation.