IMT are neoplastic mesenchymal proliferations that occur predominantly in children and young adults. Cytogentic studies of IMT show various complex karyotypic abnormalities, frequently involving the short arm of chromosome 2 harboring the ALK gene locus in 2p23.1-p23.2. The ALK (anaplastic lymphoma receptor tyrosine kinase, a.k.a. CD246) gene encodes a receptor tyrosine kinase and was frequently identified as a fusion partner of various hybrid genes predominantly in anaplastic large cell lymphoma, and more recently, in non-small cell lung cancer. However, also in IMT several different ALK fusion genes have been identified including CARS-ALK.
