Plain Language Summary of
"DNAJB1-PRKACA-positive metastatic fibrolamellar carcinoma with unknown primary in a pediatric patient"
Fusions of small segment of the protein DNAJB1 onto the front of the protein PRKACA has been found in hundreds of fibrolamellar tumors. This raised the question of whether this fusion of DNAJB1-PRKACA, might be found in other tumors. In these two papers the authors report finding the fusion of DNAJB1-PRKACA in a a few pancreatic neoplasms and a peritoneal carcinomatosis. This work strengthens the link between the DNAJB1-PRKACA and tumorigenesis. It leaves the question of why this fusion is seen so frequently in the liver.
Fibrolamellar carcinoma (FLC) is a rare variant of hepatocellular carcinoma, occurring in children and young adults without underlying liver disease. The diagnosis is based on morphological characteristics of the tumor, supplemented by immunohistochemistry and/or genetic testing. Recently, the presence of a characteristic DNAJB1-PRKACA fusion gene has been associated with FLC. Herein, we report a case of FLC presenting as peritoneal carcinomatosis in a 14-year-old female. Interestingly, no liver tumor was seen on imaging, and an alternative possibility is that the tumor arose outside the liver as a hepatoid carcinoma with fibrolamellar features.