Characteristic Of Inflammatory Myofibrinoblastic Tumor: Retrospective Analysis Of 4 Cases In Children Hospital Number 2

Abstract

Introduction: Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor that involves various organs. Surgery is the mainstay of therapy for this tumor. Approximately half of all IMT cases have anaplastic lymphoma kinase (ALK) rearrangements; therefore, the ALK inhibitor crizotinib is suggested as a promising treatment for unresectable cases with ALK rearrangements. In cases withoutALK rearrangement, chemotherapy is an alternative treatment for unresectable tumors. Cases report: We report 4 cases of IMT treated in Children Hospital Number 2 since 2018. There was one case with mesenteric tumor, one with perineal tumor detected at birth, one with inferior mediastinal tumor and one with intestinal tumor. We evaluated ALK expression by immunohistochemistry and ALK rearrangement by fluorescence in situ hybridization (FISH) in 3 cases and all negative. Treatments included tumor resection or biopsy and chemotherapy with methotrexate (30mg/m2) day 1 and vincristine (1.5mg/m2) day 1 and 7 in a 3 week cycle together with NSAID or steroid for inflammatory control. There was one case with complete response to surgery and chemotherapy; the other 3 cases ended in death due to tumor recurrence (3 cases) and metastasis (1 case). Conclusions: IMT has a diverse clinical presentation, appears in many different locations, and the clinical course can progress quickly with high rate of recurrence after incomplete surgical resection. Surgery is the optimal approach, but in those without complete resection and in those with tumor progression, tyrosine kinase inhibition should be considered if there is ALK rearrangement. In the absence of ALK rearrangement, additional tyrosine kinase rearrangements and other potentially efficacious chemotherapy regimens need to be studied for these patients.