Chordomas: pathological features; ploidy and silver nucleolar organizing region analysis. A study of 36 cases.

Chordomas are slow growing malignant neoplasms with a prolonged clinical course which do not usually metastasize. They are histologically benign, locally invasive and often recur following resection. Survival has been shown to vary widely and prognostic indicators have been difficult to identify. Cellularity, mitotic activity and cellular pleomorphism have not been found to have prognostic significance. Thirty-six cases of clival, cervico-thoracic and sacral chordomas were evaluated utilizing four variables as possible predictors of survival: (1) silver nucleolar organizing region (AgNOR), (2) ploidy, (3) fibrosis, and (4) inflammatory response. AgNOR areas in approximately 200 cells per case were calculated and summed. DNA ploidy was obtained in 23 of the cases by analyzing deparaffinized Feulgen-stained tissue. Fibrosis and inflammation were evaluated by hematoxylin and eosin and by trichrome stains. Clinical follow-up was available in the 36 cases with survival ranging from 0.5 to 159 months. A statistical analysis employing the Cox-Proportional Hazards model disclosed no significant correlation between AgNOR area and clinical outcome (P > 0.05). The variables, fibrosis, and inflammation, did not demonstrate prognostic significance (P > 0.05). Ploidy demonstrated a statistical trend for prognostic significance (P = 0.077). It is apparent that three of the four parameters studied do not independently affect survival. Although AgNOR has proved useful in the study of other neoplasms such as those of breast, prostate and bladder, it is not of significant importance in predicting the behaviour of chordomas. Ploidy, on the other hand, may be of value in predicting clinical outcome in chordomas and may be a useful marker in the evaluation of the aggressive biological behavior of these neoplasms.