We report on a 4.5-year-old boy with interstitial monosomy 9p in a unique and complex de novo rearrangement. The patient had been referred for craniofacial dysmorphism, delayed psychomotor development, and various congenital malformations. We combined cytogenetic studies and FISH analyses to delineate the deletion. The result of our cytogenetic studies was 46, XY, der(9)(p22pter). In order to confirm the deletion, we also performed FISH analysis, which showed that the 9p subtelomeric region was inserted into chromosome 13. Molecular karyotyping was performed to describe the exact genomic breakpoints of the rearrangement. In conclusion, this case is a complex insertion/deletion abnormality which has not been reported before. (C) 2016 S. Karger AG, Basel.