Chordoma: the nonsarcoma primary bone tumor.Oncologist. 2007 Nov;12(11):1344-50.

Chordomas are rare, slowly growing, locally aggressive neoplasms of bone that arise from embryonic remnants of the notochord. These tumors typically occur in the axial skeleton and have a proclivity for the spheno-occipital region of the skull base and sacral regions. In adults, 50% of chordomas involve the sacrococcygeal region, 35% occur at the base of the skull near the spheno-occipital area, and 15% are found in the vertebral column. Craniocervical chordomas most often involve the dorsum sella, clivus, and nasopharynx. Chordomas are divided into conventional, chondroid, and dedifferentiated types. Conventional chordomas are the most common. They are characterized by the absence of cartilaginous or additional mesenchymal components. Chondroid chordomas contain both chordomatous and chondromatous features, and have a predilection for the spheno-occipital region of the skull base. This variant accounts for 5%-15% of all chordomas and up to 33% of cranial chordomas. Dedifferentiation or sarcomatous transformation occurs in 2%-8% of chordomas. This can develop at the onset of the disease or later. Aggressive initial therapy improves overall outcome. Patients who relapse locally have a poor prognosis but both radiation and surgery can be used as salvage therapy. Subtotal resection can result in a stable or improved status in as many as 50% of patients who relapse after primary therapy. Radiation therapy may also salvage some patients with local recurrence. One series reported a 2-year actuarial local control rate of 33% for patients treated with proton beam irradiation.

Intraosseous benign notochord cell tumors (BNCT): further evidence supporting a relationship to chordoma.Am J Surg Pathol. 2007 Oct;31(10):1573-7.

BACKGROUND: Previous studies have documented the existence of intraosseous benign notochordal cell tumors (BNCTs) within the axial skeleton. Evidence suggests that they may be associated with the development of chordomas. To further investigate the relationship between BNCT and classic chordoma, we reviewed a large series of resected sacral/coccygeal chordomas in an attempt to identify the presence of coexisting BNCTs. DESIGN: Eighty-two sacrectomy/coccygectomy specimens performed for chordoma were identified. Available hematoxylin and eosin slides were reviewed to identify BNCTs and assess their relationship with the coexisting chordoma. BNCTs were defined, in accordance with prior descriptions, as cohesive aggregates of large cells that appeared adipocyte-like because of their vacuolated cytoplasm. The cells exhibited only minimal nuclear atypia and lacked lobulation and myxoid stroma. RESULTS: We identified 6 BNCTs, each was adjacent to but separate from the sacral chordoma. There were 5 females and 1 male, and the mean age was 58 years. Five lesions arose in the sacrum. One lesion arose in the coccyx, and involved 2 contiguous vertebral levels. The BNCTs ranged in size from 1 to 20 mm with a mean size of 6.1 mm. The lesions were exclusively composed of adipocyte-like nuclei without significant nuclear atypia or myxoid stroma. Three lesions contained sclerotic bony trabeculae and intralesional hematopoietic elements were identified in 1 case. In all cases the chordoma was of the conventional type and were morphologically different from the BNCT. CONCLUSIONS: BNCTs were identified in 7.3% of sacral/coccygeal resections performed for primary chordoma. We speculate that this finding provides further evidence that BNCT is the precursor lesion for chordoma. Additional investigations are needed to further understand this relationship.