Inflammatory myofibroblastic tumor of the posterior mediastinum: an older adult case with anaplastic lymphoma kinase abnormalities determined using immunohistochemistry and fluorescence in situ hybridization.

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm that usually occurs in children and young adults. Anaplastic lymphoma kinase (ALK) abnormalities in IMT, determined using immunohistochemistry and/or molecular genetic studies, including fluorescence in situ hybridization (FISH), have almost been limited to children and young adults. In elderly cases of IMT, these ALK abnormalities are very rare. We report on a case of IMT arising in the posterior mediastinum of a 59-year-old Japanese man that showed ALK abnormalities determined using immunohistochemistry and FISH, suggesting the neoplastic nature of a subset of IMTs in older patients similar to those in younger ones and the presence of an additional mechanism(s) that allows them to start to grow late.