Navigating Diagnostic Challenges in Epithelioid Sarcoma: Multidisciplinary Strategies to Optimize Diagnosis

EP: 1.Epithelioid Sarcoma: Overview and Presentation

EP: 2.Epithelioid Sarcoma: Histological Features and Differential Diagnoses

EP: 3.Confirming Epithelioid Sarcoma: Diagnostic Approach, Imaging, and Molecular Markers

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EP: 4.Navigating Diagnostic Challenges in Epithelioid Sarcoma: Multidisciplinary Strategies to Optimize Diagnosis

Summary for Physicians: Diagnostic Challenges and Pitfalls in ES

Diagnosing ES is often challenging due to its rarity, variable presentation, and histologic overlap with other conditions. Common diagnostic pitfalls include misinterpreting ES as benign lesions such as granulomatous inflammation or reactive processes, especially in the early stages. The tumor’s epithelioid appearance may also lead to misclassification as carcinoma or other soft tissue sarcomas.

Timely diagnosis is complicated by the typically indolent growth of ES, especially in the distal (classic) subtype, which can delay clinical suspicion. The proximal (large cell) subtype can mimic other high-grade sarcomas or poorly differentiated carcinomas due to its more aggressive features and deep-seated location.

ES is frequently misdiagnosed—often initially mistaken for infections, benign cysts, or other sarcoma subtypes. A key diagnostic marker is loss of INI1 (SMARCB1), which should be assessed in cases with ambiguous histology. Awareness of these diagnostic nuances and incorporating molecular testing early in the workup can significantly improve diagnostic accuracy.