Intraosseous benign notochordal cell tumours: overlooked precursors of classic chordomas?

Abstract

Aims: Intraosseous benign notochordal cell tumour is a recently recognized condition that may undergo malignant transformation to classic chordoma. The aim of this study was to describe its clinicopathological characteristics. Methods and results: One hundred vertebral columns from atlas to coccyx and 61 pieces of the clival portion of the skull base, which were dissected from 100 autopsy cases, were examined microscopically. Twenty-six intraosseous benign notochordal cell tumours were found in 20 cases. The patient group consisted of 15 males and five females with a mean age of 63 years. The results, according to anatomical segments, showed that 11.5% of the clivus, 5.0% of the cervical vertebrae, 0% of the thoracic vertebrae, 2.0% of the lumbar vertebrae, and 12.0% of the sacro-coccygeal vertebrae were affected. Microscopic examination revealed well demarcated but unencapsulated sheets of bland physaliphorous cells mimicking adipocytes. The lesions lacked any intercellular myxoid matrix. The affected bone trabeculae were characteristically sclerotic. Conclusions: The study indicated a surprisingly high incidence of intraosseous benign notochordal cell tumours. The anatomical distribution of the tumours was identical to that of classic chordomas. The results support other evidence that classic chordomas develop from intraosseous benign notochordal cell tumours.