2019 Volume 33 Issue 6 Pages 613-618
The solitary fibrous tumor (SFT) is a rare mesenchymal tumor that arises most commonly from the pleura. The NAB2-STAT6 fusion gene has been reported as a driver mutation of SFT. Here, we encountered a rare case of SFT that arose in lung parenchyma, and we identified the NAB2-STAT6 fusion gene in that tumor. The patient was a 73-year-old man who was noted to heve a growing mass on a chest radiograph. CT showed a circumscribed mass in the right lower lobe (S8). FDG-PET showed slight uptake of FDG in the tumor and the maximal standardized uptake value (SUVmax) was 2.59. Transbronchial lung biopsy failed to obtain an adequate amount of tissue. Because the possibility of lung cancer was suspected, a right lower lobectomy and mediastinal lymph node dissection were performed. Histopathological examination showed the dense growth of tumor cells with oval nuclei. Immunohistochemical examination showed diffuse staining for CD34, CD99, bcl-2, and strong positivity for STAT6, indicating a diagnosis of intrapulmonary SFT. We extracted RNA from the tumor and identified the NAB2 (exon 4) - STAT6 (exon 2) fusion gene using RT-PCR (reverse-transcriptase polymerase chain reaction) and direct sequencing.
