Malignant triton tumor with thoracic region as the initial presentation: a case report.

Background: Malignant Triton Tumor (MTT) is a rare, highly aggressive peripheral nerve sheath tumor characterized by rhabdomyoblastic differentiation, seldom occurring primarily in the thoracic cavity. This report presents a rare case of MTT initially manifesting as chest pain, and reviews relevant literature to summarize its clinical features and therapeutic strategies. Methods: A 23-year-old woman experienced chest pain for ten days and her condition worsened within 3 days. The patient had a known history of neurofibromatosis type 1 (NF1) and exhibited classic café-au-lait spots on physical examination. Diagnosis was confirmed via chest CTA, PET-CT, bronchoscopy, ultrasound, and histopathology. After surgical resection, the tumor recurred rapidly, prompting multiple treatments including chemotherapy, targeted therapy, and combination immunotherapy. Results: Pathology after right lower lobectomy and chest wall resection confirmed MTT (S-100+/Desmin+/Myogenin+). Recurrence in the mediastinum was detected two months postoperatively. Disease stabilization was achieved using cadonilimab, apatinib, and ifosfamide/etoposide. Notably, the first application of single-cell RNA sequencing (scRNA-seq) in MTT, combined with the CopyKAT algorithm, distinguished malignant from non-malignant cells and revealed a heterogeneous tumor microenvironment composed of distinct functional cell populations, highlighting the tumor's high degree of heterogeneity. Conclusion: This case underscores the importance of considering MTT in young NF1 patients presenting with intrathoracic masses. An individualized, multimodal treatment approach may extend survival. scRNA-seq provides valuable insights into the molecular landscape of MTT and hold promise for guiding precision therapy in the future.