Double amplifications of CDK4 and MDM2 in a gastric inflammatory myofibroblastic tumor mimicking cancer with local invasion of the spleen and diaphragm

ABSTRACT

Inflammatory myofibroblastic tumor (IMT) is currently recognized as an intermediate mesenchymal neoplasm. It can arise anywhere in the body, but it is particularly common in the lungs. Gastric IMT is very rare in adults. In this study, we report a case of a 68-year-old woman with IMT in the gastric cardia, with invasion into the spleen and diaphragm. Because of its location and aggressive clinical features, it was first mistaken for gastric cancer. However, pathology and immunohistochemistry were used to finally confirm the diagnosis of IMT after total resection of the tumor and spleen and partial resection of the diaphragm. In order to provide better understanding of this rare tumor, targeted next-generation sequencing (NGS) and IHC were performed to assess genetic and protein abnormalities of the tumor. Both IHC and NGS were found to be negative for ALK or other gene fusions. However, double amplification of CDK4 and MDM2 were found by NGS, and IHC also found CDK4 and MDM2 to be positive. To the best of our knowledge, this is the first gastric IMT report to show double invasion of the spleen and the diaphragm, and double amplification of CDK4 and MDM2 in IMT are also reported for the first time. This genomic aberration with protein overexpression is the most likely tumorigenic driver of this rare and aggressive tumor.

Keywords:

• Inflammatory myofibroblastic tumor (IMT)
• stomach
• spleen
• diaphragm
• MDM2 amplification
• CDK4 amplification
• ALK-negative

Acknowledgments

The authors thank Burning Rock Biotech for providing excellent NGS technical support. We are also grateful to the MDT team of the Peking Union Medical College Hospital for their support.

Additional information

Funding

This work was supported by the the CAMS (Chinese Academy of Medical Sciences) Fundamental Research Fund for Central Public Welfare Research Institute [2017PT31009].