Diagnostic Dilemma and Therapeutic Challenges in EWSR1::PATZ1 Fusion Sarcomas: Insights From Two Patients

Round cell sarcoma with EWSR1::PATZ1 fusion is an extremely rare sarcoma of soft tissue and bones that comes under EWSR1::non-ETS fusion sarcoma. Molecular studies, such as next-generation sequencing, are essential for accurate diagnosis, as this tumor presents as conventional round cell sarcoma, often co-expressing myogenic and neurogenic markers, which can prompt an erroneous diagnosis of rhabdomyosarcoma (RMS) or malignant peripheral nerve sheath tumor. Due to the rare incidence and paucity of literature on this tumor, the definite prognostic implications and therapeutic guidelines are lacking. Here, we describe two patients with EWSR1::PATZ1 sarcoma, of which one patient was initially misdiagnosed as synovial sarcoma and RMS on two occasions. These patients underscore the diagnostic challenges and therapeutic uncertainties surrounding EWSR1::PATZ1 fusion sarcomas, emphasizing the need for further large collaborative studies to establish optimal prognostic implications and management strategies for this rare entity.