Accuracy of histological grades from intraoperative frozen-section diagnoses of soft-tissue tumors.

Background: For excised tumor specimens, histological grades can differ between the biopsy diagnosis and the final diagnosis.
Methods: We retrospectively investigated the diagnostic accuracies of histological grades for frozen-section and permanent-section diagnoses from patients with soft-tissue tumors. Frozen-section, permanent-section, and final diagnoses were classified as benign tumors/tumor-like lesions, intermediate malignancies, or malignant tumors. Diagnostic accuracies of the histological grades from the frozen and permanent sections were evaluated by comparing the final diagnoses for the resected specimens.
Results: The diagnostic accuracies of the histological grades for the frozen- and permanent-section diagnoses were 95% (387/408 lesions) and 97% (395/408 lesions), respectively. Among the tumor types, the diagnostic accuracies of the histological grades for the frozen-section and permanent-section diagnoses were 84% and 87% for adipocytic tumors, 87% and 91% for fibroblastic/myofibroblastic tumors, 99% and 100% for nerve-sheath tumors, 98% and 98% for fibrohistiocytic tumors, 90% and 98% for tumors of uncertain differentiation, 100% and 100% for vascular tumors, and 97% and 98% for other tumors, respectively.
Conclusions: Histological grades from frozen-section diagnoses yielded low diagnostic accuracies in adipocytic and fibroblastic/myofibroblastic tumors. Treatment should be planned based on permanent-section diagnosis and radiological findings for these tumors.