Common Pitfalls in Ewing Sarcoma and Desmoplastic Small Round Cell Tumor Diagnosis Seen in a Study of 115 Cases.

Nikolaos A Trikalinos,John S A Chrisinger,Brian A Van Tine

doi:10.3390/medsci9040062

Abstract

Ewing sarcoma (ES), “Ewing-like sarcoma” (ELS) and desmoplastic small round cell tumors (DSRCT) can masquerade as other tumor types, particularly neuroendocrine neoplasms and receive inappropriate treatment. We retrieved 115 cases of ES, ELS and DSRCT seen over 17 years in a tertiary center. An initial misdiagnosis or incomplete diagnosis occurred in 6/93 (6.4%) of ES/ELS and 5/22 (22.7%) of DSRCT cases. The most frequent misdiagnosis was small cell neuroendocrine carcinoma. While any misdiagnosis or incomplete classification is almost certainly multifactorial, the most common identified reason for erroneous/incomplete initial reporting was expression of neuroendocrine markers. Other contributing factors included keratin expression, older patient age and apparently unusual tumor location. Most patients treated with a non-sarcoma chemotherapy regimen expired, while those who received a sarcoma-related regimen were alive as of last evaluation. Increased awareness of this diagnostic pitfall is needed in evaluating cases of round cell malignancies.

Highlights

Ewing sarcoma (ES) and desmoplastic small round cell tumors (DSRCT) are aggressive, rare sarcomas with a respective incidence of about 1 case and 0.5 cases per million [1] per year in North America
Under an institutional review board (IRB) approval, we used a coding algorithm to retrieve pathology files of patients diagnosed with ES, Ewing-like sarcomas” (ELS) and DSCRT from 2003 to 2020 at our institution
We examined 115 patients with ES/ELS and DSCRT seen in our tertiary center over more than 15 years, documented all potentially treatment changing incompletely or misdiagnosis cases and speculated on the reasons behind it

Summary

Introduction

Ewing sarcoma (ES) and desmoplastic small round cell tumors (DSRCT) are aggressive, rare sarcomas with a respective incidence of about 1 case and 0.5 cases per million [1] per year in North America Both commonly present with a round cell pattern, but they can be differentiated by a combination of clinical, histologic, immunohistochemical and molecular findings. Other undifferentiated small round cell sarcomas (USRCS), some previously known as “Ewing-like sarcomas” (ELS), make up a diverse group of sarcomas with round (and not so round) cytomorphology including round cell sarcomas with EWSR1-non-ETS fusions, CIC-rearranged sarcoma and sarcoma with BCOR genetic alterations [3] Despite their relative aggressiveness, rapid identification and initiation of long-term chemotherapy, in combination with surgical and radiation approaches, can have substantial effect on the outcomes of these diseases. This can lead to suboptimal outcomes and missed opportunities for cure

Methods

Discussion

Conclusion