International Surgery Journal | September 2021 | Vol 8 | Issue 9 Page 2852 International Surgery Journal Ahire PP et al. Int Surg J. 2021 Sep;8(9):2852-2855 http://www.ijsurgery.com pISSN 2349-3305 | eISSN 2349-2902 Case Report Primary subcutaneous extra skeletal Ewing’s sarcoma: a case report on a very rare clinical entity Priya P. Ahire 1 , Pramod D. Nichat 1 , Kashif F. Ansari 1 , Vismaya K. B. 1 *, Kuldeep Parmar 1 , Aishwarya Mohanraj 1 , Akshay V. Kadam 1 , Subhash Yadav 2 INTRODUCTION Ewing sarcoma is a tumour which normally affects the bones (90%), and to lesser extent the soft tissues (10%). The tumour is very rare, even though it is the second most common bone malignancy found in children. Under the microscope, it is formed by small cells with round hyper chromatic nuclei and a single nucleolus. The cytoplasm is poorly defined, scarce, of clear coloration and with irregular vacuoles resulting from intracellular deposits of glycogen. Immunohistochemically, the cells usually express CD99 and are characterized by a specific chromosomal translocation involving gene EWSR1 in chromosome 22 with an erythroblastosis virus transforming gene, resulting in a fusion oncogene. 1,2 Since the histology and immune histochemical profile are also relatively nonspecific, many differential diagnoses must be considered, such as Merkel cell carcinoma, cutaneous lymphomas, malignant primitive neuroectodermal tumour or rhabdomyosarcoma. 3 Patients affected are mostly females with the predilection being 1.9:1, according to Di Giannatale et al. According to Delaplace et al, the female to male ratio is 3:1. The median age of diagnosis is 17 years, however in most patients due to difficulty in diagnosing such a rare case, the malignancy would have metastasized (the median time of diagnosis after the onset of symptoms in a case of extra skeletal Ewing’s sarcoma is roughly 3-5 months, enough time for a tumour to metastasize and become incurable). Treatment is mainly surgery. Adjuvant chemotherapy and radiotherapy can also give depending extent of disease. 4 CASE REPORT The patient is a 35-year-old female who initially came to the OPD with complaints of mass on the left trunk for 1 ABSTRACT Primary extra skeletal Ewing’s sarcoma is a very rare clinical entity. Patients are normally females in the second decade of their life. Clinically it normally presents as a fleshy mass which is mobile, not attached to the underlying structures. Diagnosis is difficult, final diagnosis being made by histopatholoical, immunohistochemistry and cytoskeletal studies combined. Ewing’s sarcoma is a tumour which normally affects the bones, and to a much lesser extent (10%) the soft tissues. Primary extra skeletal Ewing’s sarcoma affecting the back (as in the case we are discussing) is an extremely rare clinical entity with lesser than 50 cases reported worldwide. The entity being so rare doesn’t have any much literature for review. Keywords: Ewing’s sarcoma, Extra skeletal, Immunohistochemistry 1 Department of General Surgery, Grant Government Medical College and J. J. Group of Hospitals, Mumbai, Maharashtra, India 2 Department of Pathology, TATA Memorial Hospital and Homi Bhabha Research centre, Mumbai, Maharashtra, India Received: 25 July 2021 Revised: 13 August 2021 Accepted: 17 August 2021 *Correspondence: Dr. Vismaya K. B., E-mail: vismayakb99@gmail.com Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. DOI: https://dx.doi.org/10.18203/2349-2902.isj20213635