A recurrent inflammatory myofibroblastic tumor patient with two novel ALK fusions: a case report

BACKGROUND: Inflammatory myofibroblastic tumor (IMT) is a rare disease that mainly involves the lung and the abdomen. The gold standard of the IMT treatment is radical surgery, while chemotherapy and radiotherapy are represented usually for unresectable lesions. Anaplastic lymphoma kinase (ALK) rearrangements are present in approximately 50% of IMT patients, and several clinical trials of ALK tyrosine kinase inhibitors (TKIs) in the treatment of ALK-positive IMT patients are underway. CASE DESCRIPTION: We reported a case of IMT in the right pelvic cavity. Initially, the patient underwent resection of multiple lesions. Unfortunately, the patient’s tumor recurred half a year later, and enhanced computerized tomography (CT) of the whole abdomen revealed multiple low-density masses. Then the patient underwent resection of the recurrent tumors. Immunohistochemical staining exhibited the expression of ALK in the tumor cells, and next-generation sequencing (NGS) technology revealed two novel ALK fusions, ALK-ribosome binding protein 1 (RRBP1) and hydroxyacid oxidase 1 (HAO1)-ALK fusions. These fusions were able to be transcribed and captured by RNA level. And the two fusions have not been reported in the IMTs. CONCLUSIONS: This case expanded the range of ALK fusion types and provided a promising molecular-targeted treatment strategy. In addition, the two novel ALK fusions may be the recurrent oncogenic mechanism in clinically aggressive IMT.