INSM1 Expression in Chordomas.

ABSTRACT

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.