EXTRASKELETAL EWING SARCOMA OF SCAPULAR SOFT TISSUE MIMICKING LIPOSARCOMA: A DIAGNOSTIC CHALLENGE IN A YOUNG FEMALE

Abstract

Antimicrobial resistance (AMR) has become one of the most serious global public health threats, driven by the rapid Ewing sarcoma is the second most common frequent malignant bone tumor in children and adolescents, with neuroectodermal characteristics. Extra skeletal Ewing sarcoma (EES) is a rare, aggressive small round-cell tumor that develops in soft tissues without primary bone involvement, with a slight male predominance. Due to its rarity and overlapping features with other soft tissue tumors, EES poses a significant diagnostic challenge, especially at atypical anatomical sites. We report a case of 21-year-old female who came with complaints of swelling over the right scapular region. Radiological examination suggestive of liposarcoma, while histopathological examination showed features of malignant small round cell tumor, without underlying scapular bone involvement. Immunohistochemistry showed CD99 positivity and Ki- 67 labeling index of approximately 25%. Molecular analysis couldn’t be done due to resource limitation, However the diagnosis was established by integrating histopathological morphology, immunohistochemistry (CD99-positive), and clinicoradiological correlation. EES arises from the long bones of the extremities more commonly, however this case highlights a rare occurrence in the soft tissue overlying a flat bone (scapula) without bony involvement. This unsual anatomical location, particularly in a young female, and the imaging findings mimicked liposarcoma, creating a significant diagnostic challenge. Although molecular confirmation is considered the diagnostic gold standard, it was not feasible in our institute due to resource limitations. Nevertheless, the diagnosis of EES was reliably established through a comprehensive and evidence-based approach integrating characteristic histomorphology, strong membranous CD99 immunopositivity, and clinic radiological correlation. This multimodal diagnostic strategy is well-recognized as an acceptable alternative in resource-limited settings. This case highlights the importance of considering Ewing sarcoma in the differential diagnosis of soft tissue masses at atypical sites for accurate diagnosis and early management.