Multimodal treatment achieves durable radiologic remission in adult primary pulmonary embryonal rhabdomyosarcoma

Introduction: Primary pulmonary rhabdomyosarcoma (PPRMS) is an exceedingly rare thoracic sarcoma in adults, and evidence-based treatment strategies are not established. Case presentation: A 71-year-old Han Chinese man with prior esophageal rupture repair and no smoking history was found to have a right lower hilar mass. Baseline clinical assessment showed preserved self-care capacity, with a Karnofsky Performance Status of 80%. Bronchoscopy identified a friable cauliflower-like endobronchial neoplasm obstructing the right lower lobe bronchus. Biopsy and immunohistochemistry showed embryonal-type PPRMS, including focal/partial positivity for myogenic differentiation 1 (MyoD1), myogenin, and desmin and a Ki-67 index of approximately 90%. The tumor was clinically staged as cT2aN1M0 (Stage IIB), although the hilar node and small pulmonary nodules were not pathologically confirmed and positron emission tomography-computed tomography (PET-CT) was not performed. Because surgery was not feasible, the patient received cisplatin, nab-paclitaxel, and adebrelimab every 21 days for six cycles plus curative-intent intensity-modulated radiotherapy (66 Gy in 30 fractions) between cycles 4 and 5. Serial chest computed tomography (CT) showed near-complete resolution of the primary mass and improvement in hilar adenopathy, and bronchoscopic follow-up approximately 9 months after diagnosis showed no endobronchial neoplasm. Patient-assessed symptom burden during initial treatment consisted mainly of manageable nausea and fatigue. A later pulmonary event caused dyspnea with routine activities and improved after oxygen support and glucocorticoid-based management. Conclusions: This case documents durable clinical and radiologic remission after individualized multimodal treatment in an elderly patient with adult PPRMS. The observation is hypothesis-generating and cannot establish the independent efficacy of chemotherapy, programmed death-ligand 1 (PD-L1) blockade, or radiotherapy. Missing PET-CT, nodal or pulmonary-nodule biopsy confirmation, PD-L1 testing, and molecular profiling limit biological interpretation.