Clinicopathologic analysis of misdiagnosed extraskeletal Ewing′s sarcoma in children / 中华实用儿科临床杂志

ABSTRACT

Objective:To investigate clinicopathological characteristics of misdiagnosed pediatric extraskeletal Ewing′s sarcoma in children, its diagnosis and differential diagnosis, and the reasons of misdiagnosis by pathologists.Methods:The clinical data of 34 cases of pediatric extraskeletal Ewing′s sarcoma diagnosed by the Department of Pathology, Xi′an Children′ Hospital and Xijing Hospital Fourth Military Medical University from January 2011 to July 2019 were retrospectively analyzed.Hematoxylin-eosin staining, immunohistochemical staining and EWSR1 fusion gene detection by fluorescence in situ hybridization (FISH) were performed on 6 primarily misdiagnosed cases.The clinical features, histological morphology, immunophenotype and molecular genetics of these 6 patients were studied. Results:The median age of 6 cases was 7 years old.There were 5 cases with slowly-growing, painless and localized masses.Four masses were located in the superficial subcutaneous fascia, and 1 was a rapidly growing soft tissue mass.Tumor cells were lobular and nest-like under low power microscopy.At high power microscopy, 2 cases were composed of small blue round cells, and 4 cases had morphological changes, including an increase in cell volume and enriched cytoplasm.Among the 4 cases with tumor morphological changes, tumor cells of 1 case had fine and smooth chromatin, tumor cells of 1 case had clear nuclei and prominent nucleoli, tumor cells of 1 case were composed of epithelioid cells, and tumor cells of 1 case were mixed spindle and epithelioid cells in large round and oval cells.The positive rates of CD 99, friend leukaemia integration-1(FLI1) and ERG were 5/6 cases, 5/6 cases and 2/6 cases, respectively.Rearrangements of EWSR1 gene were detected in all 6 cases. Conclusions:Biological characteristics including young onset age, superficial position and primary benign tumor, histological diversity and atypical immunohistochemical markers are 3 important factors contributing the misdiagnosis of extraskeletal Ewing′s sarcoma in children.The diagnosis should be made by combining the clinical features, morphology, immunohistochemical staining and EWSR1 gene detection.