LAUSR

Ewing sarcoma (ES) is the second most common bone malignancy in young patients, with 80% occurring in the first two decades of life. In contrast, extraskeletal ES accounts for approximately 12% of cases and is more common in older patients.[1] The clinical behaviour is aggressive, with a 5-year survival of 70-80% for localized disease, less than 30% for metastatic or early-relapsing disease, and possibly a worse prognosis in adults compared to children.[1,2] ES is defined by FET-ETS family gene fusions. The majority of cases harbour t(11;22)(q24;q12) translocations, corresponding to EWSR1-FLI1 fusion (85%), or t(21;22)(q22;q12) resulting in EWSR1-ERG (10%).[1] Herein we report the case of an FUS-ERG fusion-positive extraskeletal ES, which exhibited an indolent natural history over 25 years without any intervention, diagnosed via endobronchial ultrasound-guided fine-needle aspiration (EBUS-FNA) biopsy following progression.