It has been reported that the upstream frameshift 1 mutation downregulates nonsense-mediated RNA decay within the molecular pathways, this suppressed expression of NF-κB then plays a role in the immune system ability to infiltrate IMT signs.[10] Lee et al[7]reported a case of ALK-negative IMT in the triceps brachii which grew rapidly, resulting in ulnar nerve compression symptoms in this patient, MRI features were similar to those in our case, the tumor was surgically resected and the patient condition improved with no recurrence after 12-month follow-up. Here, NFKB1 is linked to inflammatory myofibroblastic tumor.