Objective In cancer patients, the pathology report serves as an important basis for treatment. Therefore, a correct cancer diagnosis is crucial, and diagnostic discrepancies may be of clinical relevance. It was the aim of this study to perform a specialized histopathology review and to investigate potential clinical implications of expert second opinion pathology in endometrial cancer.

Methods Patients treated for endometrial carcinoma at the Tübingen University Women's hospital between 2003 and 2013 were identified. Original pathology reports were reviewed, and contributing pathologists were asked to submit original slides and paraffin blocks. Case review was subsequently performed by 3 pathologists specialized in gynecological pathology who were blinded for clinical information. For histological typing, the World Health Organization 2014 classification was used, grading and staging were performed according to International Federation of Gynecology and Obstetrics 2009. Risk assignment was performed based on the 2013 European Society for Medical Oncology clinical practice guidelines.

Results In 565 of 745 cases, which had originally been diagnosed as endometrial carcinoma, archival histological slides and blocks were available. In 55 (9.7%) of 565 cases, a major diagnostic discrepancy of potential clinical relevance was found after expert review. In 38 of these 55 cases, the diagnostic discrepancy was related to tumor type (n = 24), grade (n = 10) or myoinvasion (n = 4). In 17 cases, the diagnosis of endometrial carcinoma could not be confirmed (atypical hyperplasia, n = 10; endometrial carcinosarcoma, n = 4; neuroendocrine carcinoma, n = 1; leiomyosarcoma, n = 1; atypical polypoid adenomyoma, n = 1). Minor discrepancies not changing risk classification were also noted in 214 (37.9%) of 565, most frequently for grade within the low-grade (G1/G2) category (n = 184).

Conclusions A retrospective gynecopathological case review was shown to reveal limited but significant discrepancies in histological diagnoses as well as typing and grading of endometrial carcinomas, some directly impacting clinical management. Second opinion pathology therefore not only helps to improve the quality of translational research study cohorts but might also help to optimize patient care in difficult cases.