Usefulness of argyrophilic nucleolar organizer staining for histologic grading of soft-tissue sarcomas

Accurate histologic grading is essential for making a proper therapy decision in soft-tissue sarcomas (STS). The usefulness of the argyrophilic stain for nucleolar organizer region (AgNOR) in assessing the histologic grade of STS has been examined. One hundred and forty-two patients with STS confined to the extremity and trunk were selected. Tumors were classified based on the criteria of Enzinger and Weiss ["Soft-Tissue Tumors." St. Louis: C. V. Mosby, 1983]. In addition, non-specific classification was made based on the shape of proliferating cells occupying more than 50% of the field in the sections such as pleomorphic cell, small round cell, spindle cell, epithelioid cell, myxoid, and unclassified tumors. The mean number of AgNOR dots per nucleus of tumor cells was calculated in 200 cells (AgNOR count). Each category of non-specific classification was divided into a high-count group (< 8 AgNOR count) and a low-count group (> 8 NOR). The low-count group showed a significantly better prognosis than the high-count group in small round cell and spindle cell tumors (P < 0.007 and P < 0.0005, respectively). Similar results were obtained in pleomorphic cell tumors, though they were statistically not significant because of the relatively small number of examined cases. Most patients with epithelioid cell and myxoid tumors were in the low-count group. These findings suggest that the assessment of histologic grading of STS could be made effectively by the non-specific classification and the aid of AgNOR staining.