PMC4525788_01
Pathological findings of the pulmonary metastases from malignant uterine PEComa.. Notes: (A) Hematoxylin and eosin stain, magnification x100. (B and C) HMB-45 and SMA immunohistochemical stain, magnification x200. (D) Ki-67 immunohistochemical stain, magnification x200. The average Ki-67 labeling index is 40% in this tumor. Background staining was identified by negative controls in which the sections were performed by substitution of primary antibodies with phosphate buffer solution.. Abbreviations: HMB-45, human melanoma black 45; PEComa, perivascular epithelioid cell tumor; SMA, smooth muscle actin.
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PEComa with late renal and pulmonary metastases. Pulmonary metastases from malignant uterine PEComa display nests of epithelioid cells with small round nuclei surrounding thin-walled capillary vessels (Figure 1A). Tumor shows diffusely positive staining for melanocytic marker and smooth muscle marker (Figure 1B and C). A high Ki-67 labeling index of 40% indicates the aggressive behavior of the tumor (Figure 1D).
The 18F-FDG PET/CT scans of the patient.. Notes: (A and B) Axial CT image in the lung window and axial PET/CT fusion image at the level of inferior pulmonary vein. Circles: pulmonary metastases. (C and D) Axial CT image in the abdominal window and axial PET/CT fusion image at the level above hepatic portal. Arrows: liver metastases. (E and F) Axial CT image in the abdominal window and axial PET/CT fusion image at the level of hepatic portal. Boxes: metastatic foci growing from previous left kidney bed. (G) Maximum intensity projection image 18F-FDG PE T showed tumor emboli in bilateral upper pulmonary artery (arrowheads), left atrium (short arrow), and inferior vena cava (long arrow).. Abbreviations: CT, computed tomography; FDG, fluorodeoxyglucose; PET, positron emission tomography.
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The PET/CT imaging showed bilateral multiple pulmonary metastases with maximum standardized uptake value (SUVmax) of 6.5 (circles in Figure 2A and B), liver metastases with SUVmax of 12.1 (arrows in Figure 2C and D), metastatic foci growing from previous left kidney bed with SUVmax of 7.3 (boxes in Figure 2E and F). In addition, whole body FDG PET showed multiple distant metastases, including the disseminating tumor emboli with intense FDG uptake (Figure 2G).
Follow-up CT scans of the patient.. Notes: (A) Partial response was observed by CT at 3 month after the initiation of the mTOR inhibitor treatment. For example, the size of the largest lesion in lung was reduced from 9 to 4 mm (circle). Some other pulmonary metastases were cavitated (box). (B) Nearly complete response was observed by CT at 7 months after the initiation of the mTOR inhibitor treatment. Fibrosis was observed at the largest pulmonary metastatic focus (circle). No other residual lesion was discernible (box).. Abbreviations: CT, computed tomography; mTOR, mammalian target of rapamycin.
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The follow-up axial CT images (Figure 3A and B) showed that the pulmonary metastatic foci were gradually diminishing and eliminating.