case_images: PMC11096473_01
case_images: Radiograph and CT of femur. (A) Pelvic ap before pathological fracture. (B) Coronal CT scan of bilateral hip. Osteolytic bone destruction was observed in the upper left femur. (C) Left hip ap x-ray examination after pathological fracture. The femoral cortex was discontinuous, angulated and deformed, and the soft tissue was swollen. (D) Postoperative X-ray of the long-leg radiographs 15 months after treatments: the femoral prosthesis was well in place without loosening and abnormal radiolucent lines.
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case_images: Figures 1 ,  2 ). Surprisingly, after one course treatment with sintilimab combined with anlotinib, pathologic fracture of the left proximal femur occurred at the site of tumor invasion ( Figure 1 ), and the symptom of fever of undetermined origin was relieved.
case_images: Chest and Thoracic CT. (A) Sagittal CT scan of left lung. Scattered lung nodules were seen. (B) Sagittal CT scan of left lung. (C) Axial CT scan of bilateral lungs. A pulmonary cavity (20 mm x 30 mm) in the superior lobe of left lung. (D) Sagittal CT scan of left lung 15 months after treatments. The scattered lung nodules were significantly smaller than before. (E) Sagittal CT scan of left lung 15 months after treatments. (F) Axial CT scan of bilateral lungs 15 months after treatments. The left lung cavity was further reduced in size of approximately 16*0.9mm. (G) Coronal CT scan of thoracic vertebra. (H) Sagittal CT scan of thoracic vertebra. (I) Axial CT scan of thoracic vertebra. Bone destruction in thoracic six vertebra. (J) Coronal CT scan of thoracic vertebra 15 months after treatments. (K) Sagittal CT scan of thoracic vertebra 15 months after treatments. (L) Axial CT scan of thoracic vertebra 15 months after treatments. There were signs of a circular hyperdense shadow on the right side of thoracic six vertebra.
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case_images: Figures 1 ,  2 ). Further evaluation of the lung using enhanced CT scan showed a pulmonary cavity (20 mm x 30 mm) in the superior lobe of left lung and scattered lung nodules, which was considered a possible malignancy with vascular invasion multiple metastatic sites ( Figure 2 ). Femoral bone metastases were also found using emission computed tomography (ECT) and magnetic resonance imaging (MRI) ( Figure 3 ). The scattered lung nodules were also significantly smaller than before ( Figure 2 ). The range of vertebral body destruction which showed a circular hyperdense shadow on the right side of thoracic six vertebra was not significantly changed ( Figure 2 ).
case_images: MRI of femur. (A) Axial MRI scan of femur in T1WI. (B) Sagittal MRI scan of femur in T1WI. (C) Coronal MRI scan of femur in T1WI. (D) Axial MRI scan of femur in T2WI. (E) Sagittal MRI scan of femur in T2WI. (F) Coronal MRI scan of femur in T2WI. (G) Axial MRI enhanced scan of femur. (H) Sagittal MRI enhanced scan of femur. (I) Coronal MRI enhanced scan of femur.
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case_images: Further evaluation of the lung using enhanced CT scan showed a pulmonary cavity (20 mm x 30 mm) in the superior lobe of left lung and scattered lung nodules, which was considered a possible malignancy with vascular invasion multiple metastatic sites ( Figure 2 ). Femoral bone metastases were also found using emission computed tomography (ECT) and magnetic resonance imaging (MRI) ( Figure 3 ).
case_images: Postoperative pathological sections of metastatic tumors in femur. (A) HE stained sections(x100). The tumors were mainly composed of spindle-shaped cells arranged in fascicular and storiform patterns. (B) HE stained sections(x100). The tumors were arranged in nests and cords. (C) HE stained sections(x400). The tumors were arranged in nests and cords. (D) HE stained sections(x400). The nuclei were of variable size and vacuolated with visible nucleoli. (E) Immunohistochemistry CK (+). (F) Immunohistochemistry TTF1(focal +). (G) Immunohistochemistry P63(-). (H) Immunohistochemistry Vimentin (+). (I) Immunohistochemistry P40(-). (J) Immunohistochemistry Ki67(+). (K) Immunohistochemistry CK7(+). (L) Tumor specimens resected during surgery.
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case_images: TTF1(focal +), CK (+), CK8/18(+), Vimentin (+), CK7(+), EMA (+), TLE1(+), CD56(-), CD34(-), NapsinA (-), Desmin (-), P63(-), P40(-), S100(-), Ki67(+, about 50%) ( Figure 4 ). The features were consistent with PSC. Postoperative pathology sections and immunohistochemistry confirmed that the tumor in the proximal femur was metastatic sarcomatoid carcinoma ( Figure 4 ).