Histological diversity and clinical characteristics of Ewing sarcoma family of tumors in children: A series from a tertiary care center in South India

The Ewing sarcoma family of tumors (ESFT) are aggressive malignant tumors with small round cell morphology affecting mainly children and adolescents. The aim of this study is to classify the histological diversity and clinical characteristics of ESFT in children from a Tertiary Care Center in South India. This retrospective descriptive study includes 51 cases of ES in children aged below 15 years. Clinical details were collected from case files. Histomorphological features were reviewed and tumors were subtyped into classic, primitive neuroectodermal tumor (PNET) and atypical variants along with immunohistochemical markers, cytogenetics, and fluorescence in situ hybridization (FISH). Fifty-three percent were female and 47% were male with mean age of 10 years. The most common site of involvement was skeletal involvement in 71%, followed by soft tissue involvement in 23%, and visceral involvement in 6%. Localized disease at presentation was seen in 44%, locally advanced disease in 28%, and metastatic disease in 28%. Recurrence was documented during follow-up in 18% of the cases. Histomorphologically, classic type was the most common (72%) followed by PNET (20%) category and atypical variant (8%). All cases were immunoreactive for CD99. Cytogenetic study in 12 cases showed translocation t(11;22) (q24;12) in 80% and variant translocations such as t(3;16), t(3;11) with nonspecific numerical abnormalities in 20%. FISH was carried out for documentation of four cases with atypical histomorphology. ESFT had wide histological variation which required confirmation by ancillary studies.