DCTN1-ALK gene fusion in inflammatory myofibroblastic tumor (IMT) of the CNS

Inflammatory myofibroblastic tumor (IMT) is a rare neoplastic tumor type of intermediate biological potential, only recently distinguished from the non-neoplastic category of inflammatory pseudotumor (IP). The literature describes very few cases of IMTs arising in the central nervous system (CNS), and the distinguishing clinical, pathological, and molecular features of IMT-CNS are not well understood. Our purpose is to publish a case of an IMT-CNS with a novel DCTN1-ALK gene fusion, furthering in the literature’s characterization of a rare tumor type. Review of the literature included a PubMed Database search of articles found by the following searches: “Inflammatory myofibroblastic tumor;” “Inflammatory myofibroblastic tumor central nervous system;” “ALK gene fusion;” and “DCTN1-ALK gene fusion.” Inclusion of articles discovered by these search terms was determined through critical appraisal of article relevance, number of citations, cross-citation within articles of interest, and rare findings with conflicting conclusions in an effort to reduce publication bias. We present a case of IMT-CNS with several distinctive molecular features including a DCTN1-ALK gene fusion, the first of its kind described in an intracranial IMT. IMT is an infrequent tumor type and its presentation within the CNS is exceedingly rare. The paucity of cases, along with the ambiguity of terminology in the literature, has stunted accurate clinical, pathological, and molecular characterization of IMT-CNS. Our case report improves the characterization of the recently appreciated category of IMT-CNS so that connections between phenotype and prognosis, and between genotype and treatment, can eventually be made.