Soft-tissue and bone sarcoma histopathology peer review: the frequency of disagreement in diagnosis and the need for second pathology opinions. The Southeastern Cancer Study Group experience.

Histopathologic peer review of specimens from 216 consecutive patients with soft-tissue or bone sarcomas on Southeastern Cancer Study Group protocols was performed by a panel of three pathologists. Subtype of sarcoma, degree of confidence in diagnosis, and grade were compared with agreement or disagreement in pathologic opinion from the primary member institution v the pathology review panel. The most common soft-tissue sarcoma was leiomyosarcoma, followed by malignant fibrous histiocytoma, fibrosarcoma, liposarcoma, malignant schwannoma, and rhabdomyosarcoma. There was total agreement between the primary pathologist and reviewer in 66% of cases. However, 12 cases (6%) were considered on review to not be sarcomas. In 27% of cases the subtype of sarcoma was felt to be incorrect by reviewers. Discordant diagnoses were more common when the confidence of the pathologist was less and when the tumor was of higher grade. There was no improvement in frequency of agreement in the second half of the study, despite educational workshops. We conclude that histologic peer review is important in sarcoma studies and is essential in many patients with presumed sarcomas.