Figure 1 Figure 1A: CT scan at the S2 level shows a lytic soft-tissue mass within the right side of the sacrum with erosion of the anterior cortex and extending into the right anterior sacral foramen. Figure 1B,1C: CT scan (lung window) obtained at the level of the left main bronchus reveals a nodule with lobulated and speculated margin in the superior segment of the left lower lobe. The nodule also can be seen in the mediastinal window. Figure 1D-1E: 1D HE staining of S2 punctured biopsy specimen in accordance with adenocarcinoma (×40); 1E CK7 positive (×20); 1F TTF-1 positive (×20); 1G HE staining of surgery biopsy specimen in accordance with adenocarcinoma (×40)

Figure 2 Figure 2A,2B: Anteroposterior and lateral radiographs show the changes after S2 metastatic tumor excision and lumbosacral spine stabilization applied rods and screws fixation. Figure 2C,2D: CT scan shows the nodule located in the left lower lobe slightly larger than before.

Figure 3 Figure 3A,3B: PET-CT shows multiple soft-tissue density nodules in the left pleura with intense hypermetabolism and massive pleural effusion, a finding highly suspicious for extensive metastasis in the left pleura. Figure 3C: PET-CT shows intense hypermetabolism in the periphery of metastatic tumor excision area in S2, which suggests local recurrence of metastatic tumor in S2. Figure 3D,3E: Chest CT reveals extensive bilateral ground-glass opacities especially in the right side after 34 days of erlotinib therapy. A persistent moderate left-sided pleural effusion is also noted.