Coincident primary breast lymphoma and gastrointestinal stromal tumor: case series and molecular mechanisms

Ethan B Ludmir,1,* Tyler Gutschenritter,1,* Chelsea C Pinnix,1 Jillian R Gunther,1 Loretta J Nastoupil,2 Joseph D Khoury,3 L Jeffrey Medeiros,3 Bouthaina S Dabaja,1 Sarah A Milgrom1 1Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; 2Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; 3Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA *These authors contributed equally to this work Abstract: Gastrointestinal stromal tumor (GIST) is an uncommon mesenchymal tumor, and has been shown to be associated with synchronous or metachronous second malignancies. Rare cases of coincident GIST and non-Hodgkin lymphomas (NHL) have been reported previously. Here, we report two cases of GIST and coincident primary breast lymphoma, an uncommon subtype of extranodal NHL. We propose that the exceedingly low likelihood of both these cancers occurring in these two patients by chance warrants examination for possible common oncogenic pathways in these lesions, possibly involving shared anti-apoptotic mechanisms. Further research is vital to elucidate common oncogenic pathways between such rare lesions. Keywords: diffuse large B-cell lymphoma, mucosa-associated lymphoid tissue lymphoma, anti-apoptosis, gastrointestinal stromal tumor, primary breast lymphom