Figure 1. Histopathology of adrenal gland metastasis
The biopsy specimen shows diffuse sheets of proliferating and highly atypical, epithelioid cells with coagulation necrosis. The tumor cells are relatively monotonous, with eosinophilic cytoplasm, vesicular chromatin, 1–2 prominent nucleoli, and partial rhabdoid appearance.
Immunohistochemically, the tumor cells totally lacked SMARCA4 and BRM (SMARCA2 ); were negative for AE1/3, Claudin4, desmin, MyoD1, myogenin, CD99, CD56, and WT-1 proteins; and were weakly positive for synaptophysin. Based on these results, the tumor was classified as a thoracic SMARCA4 -deficient undifferentiated tumor. Driver gene screening showed negative results for EGFR, ALK, ROS-1, KRAS, andBRAF. Immunohistochemical expression of programmed death-ligand 1 (PD-L1) was found to be 10–20%. Positron emission tomography-CT showed a 3.4-cm primary tumor in the right upper lobe of the lung and metastases to the mediastinal lymph nodes, multiple bones, and bilateral adrenal glands (Figure 2). The tumor was thus staged as clinical stage IVB (cT2aN2M1c).