42. Chordoma and chondroid tumors of the skull base: A clinicopathological study

Cartilaginous tumors of the skull base are uncommon and their classification remains still debated. These neoplasms have a great tendency to local recur and are often fatal because their critical location and their progression with bone involvement, even if adjuvant radiotherapy is given after surgery. 31 patients with cartilaginous tumors of the cranial base who underwent surgery between 1984 and 1996 in our institute were studied: 17 with classical chordoma (mean age 50 y.), 10 with chondrosarcoma low-grade (mean age 37 y.), 3 mixed chondrosarcoma with chordoid elements (1) or chordoma with chondroid elements (2) ("true" chondroid chordoma) (mean age 41 y.) and 1 with dedifferentiated chordoma (sarcomatous) (age 65 y.). They were 18 females and 13 males, without predominance in different subtype. The mean age range of the patients was 46,6 years (range 11-71 years). The histological analysis was performed on Formalin or Carnoy fixed sections of the tumor specimens. To establish tumor subsets based upon immunophenotype, an immunohistochemical study was carried out with antibodies to cytokeratin, vimentin, S100, PCNA (Proliferating Cell Nuclear Antigen), and occasionally Epithelial Membrane Antigen (EMA). The morphology and the immunoreactivity, specifically for cytokeratins, allow to differentiate and to classify these tumors: chordomas are keratin immunopositive, chondrosarcomas immunonegative, and mixed tumors, with chordoid and chondroid elements, partially positive. The different subsets of cartilaginous tumors seems to be related to different prognosis. The chondrosarcoma had a better prognosis than chordoma, having longer survival: one patients was dead within 5 y. after treatment among the patients with chondrosarcoma, while 6 patients were dead in the same period after treatment in the patients with chordoma. In conclusion the study of the immunological staining pattern is critical to establish the histotype of cartilaginous tumors of the skull base and to separe distinct entity with a better prognosis.