A Novel Malignant Peritoneal Mesothelioma with STRN Exon 2 and ALK Exon 20: A Case Report and Literature Review.

Recently, several malignant peritoneal mesotheliomas (MPMs), occurring in young women without asbestos exposure and with fusion genes such as anaplastic lymphoma kinase (ALK) and Ewing sarcoma breakpoint region 1, have been reported. In the present case, we encountered MPM with STRN-ALK fusion in a 17-year-old female adolescent. The case did not respond to chemotherapy and is currently in a clinical trial of alectinib. This is the fourth reported case of MPM with STRN-ALK fusion. Of the 45 cancer cases with STRN-ALK fusion in which the fusion partners were examined, all cases except for the current case showed fusion of exon 3 of STRN and exon 20 of ALK. This is the first case with fusion of exon 2 of STRN and exon 20 of ALK. Further advances in cancer genomic medicine may help clarify the clinical significance of this new fusion. KEY POINTS: Malignant peritoneal mesotheliomas (MPMs) can occur in young women without asbestos exposure and show fusion genes that activate anaplastic lymphoma kinase (ALK) by gene rearrangement. ALK rearrangement and the fusion partner can be detected by companion diagnostics and by next generation sequencing. Patients with MPMs with ALK rearrangement may benefit from target therapy.