1981P - Histopathological diagnostic discrepancies in bone and soft tissue tumors referred to a specialist sarcoma center and its clinical impact

Background

Histopathological diagnosis of sarcomas is challenging because of their rarity, diverse histological findings, and constantly evolving diagnostic criteria. In this study, we attempted to clarify discrepancies between histopathological diagnoses made by general pathologists at referral hospitals and diagnoses made by specialist pathologists at a tertiary cancer hospital, with a focus on its clinical impact in the era of genome medicine.

Methods

We analyzed 628 specimens from 624 consecutive-referral patients, who visited a specialist sarcoma center for treatment between April 2017 and March 2019. Differences between the first diagnosis provided at another hospital by non-expert pathologists and the diagnosis reviewed by a specialist pathologist at the sarcoma center were evaluated and classified into four categories: agreement, non-agreement, specified, and de-specified.

Results

Of the 628 specimens, pathological diagnosis matched in 403 (64.2%) specimens whereas some change was noted in 225 (35.8%) specimens. The changes in pathological diagnoses were as follows: non-agreement, 153 specimens (24.3%); specified, 52 (8.3%); and de-specified, 20 (3.2%). The benign/malignant judgment had changed for 92 specimens (14.6%). The main reason for the discrepancies was the difference in interpretation of tumor histology, which accounted for 48.9% of the cases. The unavailability of immunostaining and genetic analysis accounted for 24.4% and 8.9% of the discrepancies, respectively. The treatment was changed in 91 cases (14.5%) due to changes in the pathological diagnoses. The number of changes in surgical treatment, medical treatment, and both were 40 (6.4%), 44 (7.0%), and 7 (1.1%), respectively.

Conclusions

Our study shows that over 35% of first histopathological diagnoses of bone and soft tissue tumors were modified by expert pathologists at a tertiary cancer hospital and resulted in different treatment decisions in about 15% of cases. Given the therapeutic implications of a misdiagnosis, ensuring accurate histopathological diagnosis using some public mechanisms is of vital importance in cases of these rare tumors.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Health, Labour and Sciences Research Grant, Japan.

Disclosure

The author has declared no conflicts of interest.