Cheek EH, Fadra N, Jackson RA, et al. - Researchers explored the clinical, morphologic, immunohistochemical, molecular cytogenetic and genetic features of six uterine inflammatory myofibroblastic tumors occurring in pregnant women. In this study, 31.5 was the means age of the patients. They found necrosis in three tumors and multinucleated cells in three tumors. They noted positive ALK immunohistochemistry in five tumors, and all of these had an ALK rearrangement detected by break apart fluorescence in situ hybridization (FISH). They noted that subsequent RNA sequencing of these five tumors identified a TIMP3-ALK fusion in four and a THBS1-ALK in one. RNA sequencing detected a novel TIMP3-RET fusion that was confirmed by RET break apart FISH in the ALK negative tumor. No recurrence was developed in individuals. The data indicated that ALK immunohistochemistry will identify most uterine IMTs but if ALK expression and gene studies are negative, in the appropriate morphologic context, assessment of other tyrosine kinase genes known to be more commonly altered in extrauterine IMTs such as ROS1, NTRK3, PDGFRβ and RET may be necessary for diagnostic confirmation.