Background: The adoption of molecular profiling in non-small cell lung cancers (NSCLC) have promoted the discoveries of novel anaplastic lymphoma kinase (ALK) mutation patterns including rare intergenic rearrangements. It is always meaningful to report the structure of these fusions and their responses to ALK-inhibitors for future reference. Reports of cerebral ischemic strokes caused by atrial metastases through lymphohematogeneous spread are scarce.
Case presentation: A 35-year-old woman with no history of astherosclerosis presented with sudden onset of diplopia and facial palsy. Brain MRI scan discovered multiple infarcts around cortical and subcortical areas supplied by bilateral middle cerebral arteries, the occlusions of which were confirmed by angiography. Echocardiogram revealed intracavity appendages in atriums. The histology following valve debridement displayed endocardial metastases from lung cancer on mitral and trucuspid valves. PET/CT found right lower lobe primary tumor and mediastinal lymphadenopathies. The histology of primary lung tumor suggested adenocarcinoma and a DNA-based next-generation sequencing (NGS) test uncovered an intergenic (FAM49A, RAD51AP2)-ALK (intergenic: A14) rearrangement. Further RNA-based NGS uncovered a novel SLC34A2-ALK (exon 1: exon 15) fusion. Strokes recurred after valve surgery and vegetations reappeared on the mitral valve. Alectinib 600 mg bid was administered based on molecular finding and achieved remarkable tumor regression. Neurologic symptoms were largely relieved. No new infarctions or cerebral metastases has ever been found since.
Conclusions: We report a novel SLC34A2-ALK rearrangement responding well to alectinib in a very interesting case of peripheral lung adenocarcinoma presenting with recurrent cerebral ischemic strokes due to endocardial metastases.
Keywords: ALK fusion; Endocardial metastasis; Ischemic stroke; Non-small cell lung cancer.
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