A Case Of Simultaneously Diagnosed Lung Adenocarcinoma And Endobronchial Inflammatory Myofibroblastic Tumor With Two Distinct Types Of Alk Translocation

A 61-year-old male patient was simultaneously diagnosed with lung adenocarcinoma and inflammatory myofibroblastic tumor (IMT). The lung adenocarcinoma and IMT harbored two distinct types of ALK translocation, LOC101927285-ALK, and TPM3-ALK, respectively. The ALK Ventana showed strong positivity on both lesions. The patient was therefore given an endobronchial cryotherapy and ALK inhibitor crizotinib. The tumors showed durable response however the left lung adenocarcinoma relapsed at 17th month post-crizotinib treatment. Tissue re-biopsy on the resistant tumor revealed an ALK exon 23 C1156Y missense mutation in addition to LOC101927285-ALK mutation. Further RNA-based sequence uncovered that the noncoding region rearrangement is the fusion mutation of EML4-ALK. The patient was therefore received alectinib, and the tumor exhibited partly response. Overall, it is very rare that two types of pulmonary tumors exist in one patient driven by two distinct ALK fusions, which emphasizes the necessity of gene sequencing in clinical decision-making and individualized therapy.