Discovery of recurrent MALAT1-GLI1 oncogenic fusion and GLI1 amplification to define a subset of plexiform fibromyxomas

Plexiform fibromyxomas are rare neoplasms, being officially recognized as a distinct entity among benign mesenchymal gastric tumors in the 2010 WHO Classification of Tumors of the Digestive System. Characteristically, these tumors have a multinodular/plexiform growth pattern, and histologically contain variable cellular areas of bland myofibroblast type spindle cells embedded in an abundant myxoid matrix that is rich in small vessels. As yet, nothing is known about the molecular and/or genetic features of these tumors. Here, we describe as basic genetic finding a recurrent translocation t(11;12)(q11;q13) involving the MALAT1 and the GLI1 gene in a subgroup of these tumors. The presence of the fusion transcript in our index case was validated using PCR on genomic DNA followed by Sanger sequencing.