Discordance of Histo-pathological Diagnosis of Patients with Soft Tissue Sarcoma Referred to Tertiary Care Center

Abstract

Background: Reaching the correct histo-pathological diagnosis of soft tissue sarcomas (STS) is a great challenge and is cornerstone for treatment planning. Need of expertise for diagnosis is limited due to the lack of dedicated expert sarcoma pathologists and oncologists in India. In this study we highlight the pattern of pathological diagnosis and its accuracy outside specialist centre. Methods: We performed retrospective analysis of all patients referred to us with a clinical or histopathologic diagnosis of STS over the period January 2016 to December 2017. According to the protocol, all patients had a review of histopathology diagnosis from our institute. The tissue blocks if available were reviewed and a fresh biopsy was performed when required. The histopathologic diagnosis was also reviewed in the joint clinic, giving clinico-radiological inputs to sarcoma pathologists. For the patients with outside diagnosis and discordant report, we divided them into major discrepancy (including change of diagnosis of sarcoma to benign or other histological entity that could potentially change the treatment plan) or minor discrepancy (like mild change in grade or histopathological diagnosis not affecting the treatment plan). Statistical analysis was done by SPSS ver 23. Results: There were 149 patients with median age of 36 years (range 14-77 years), and 93 patients (62.4%) were males. About 57% (85 cases) of patients had localized disease. Most common subtypes were synovial sarcoma (16%), liposarcoma (9%), soft tissue ewings sarcoma (9%), MPNST (9%), leiomyosarcoma (8%), and undifferentiated pleomorphic sarcoma (8%). Of 149 patients, 47 (31.5%) had not been worked up outside by immunohistochemistry or other molecular studies and thus comparison was not possible; while 4 patients couldn’t retrieve blocks and repeat biopsy could not be performed. Of 97 patients (biopsy = 84, FNAC = 13) who had diagnosis from outside, 37% had major discrepancy and 24% had minor discrepancy as compared with our diagnosis from the sarcoma specialists. Univariate analysis revealed that the major discrepancy was more in non-extremity than extremity STS (p = 0.003). Conclusion: Histopathologic diagnosis in more than half of patients referred from outside centers was discordant with respect to the diagnosis of our centre with major implications on 37% of cases. We believe this is due to the lack of sarcoma pathology experts, and they are virtually non-existent in the multidisciplinary clinic set up outside the tertiary care centres.

Keywords

• soft tissue sarcoma- histopathology- pathology- sarcoma- discordance