Ensartinib in a primary pulmonary -rearranged mesenchymal neoplasm harboring a novel fusion: a case report and literature review.

Anaplastic lymphoma kinase () gene rearrangements have been increasingly detected in mesenchymal neoplasms. -rearranged mesenchymal neoplasms occur mainly in superficial tissues but rarely in internal organs. Herein, we firstly report a primary lung lesion presenting as a rare -rearranged mesenchymal neoplasm. The patient diagnosed with primary pulmonary -rearranged mesenchymal neoplasm (PPAMN) received ensartinib as postoperative adjuvant therapy, achieving a disease-free survival of 10 months. Continuation of ensartinib as first-line treatment enabled him to benefit from a partial response, with a progression-free survival of 11 months. Second next-generation sequencing (NGS) revealed elevated abundance along with secondary mutation. After local radiotherapy combined with ensartinib continuation, his disease was temporarily stable for 7 months. Unfortunately, this disease became uncontrolled with an overall survival (OS) of 34 months. This is the first case of -rearranged mesenchymal neoplasm manifested as a primary lung lesion and a novel fusion was identified by NGS. The family of -rearranged mesenchymal neoplasms is expanding and ensartinib could be a potential treatment option for patients with . Repeated biopsy and NGS detection are critical to guide treatment selection at disease progression.