PMC4296267_01
Solitary osseous rectal carcinoma metastasis in 26-year-old woman.. A. Plain radiograph of left femur (anteroposterior and lateral views) shows ill-defined lytic area in proximal meta-diaphyseal region of left femur with spiculated periosteal reaction (white arrow). B. Post-contrast axial computed tomography (CT) scan shows ill-defined lytic lesion with circumferential spiculated sunburst type of periosteal reaction and ill-defined soft tissue component in proximal third of diaphysis of left femur. Lesion shows intense neovasculartiy on reformatted volume-rendered coronal images. C. Magnetic resonance image of left thigh. Hypointensity is seen in radial distribution of proximal aspect of femur on axial gradient echo sequences. Peripheral enhancement was noted in soft tissue component of femoral lesion on post-contrast gadolinium T1-weighted images.. D. Histopathological examination shows malignant tumor composed of dispersed population of large polygonal cells with moderate amount of vacuolated cytoplasm (H&E; x 100 [upper right image], x 200 [upper left image]). Tumor cells were immunopositive cytokeratin 20 (lower right image) and Cdx2 (lower left image) confirming metastatic adenocarcinoma of colonic origin. E. Positron emission tomography (PET)-CT scan was taken for staging prior to chemotherapy. Axial CT images confirm ill-defined lytic lesion seen in proximal left femur on plain radiograph, which is 18F-fluorodeoxyglucose-avid, as seen on fused axial PET-CT images.
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A radiograph of the femur was obtained which showed ill-defined lytic area in the proximal meta-diaphyseal region of the left femur with spiculated periosteal reaction (Fig. 1A). The patient underwent a computed tomography (CT) study of the pelvis and the proximal lower limbs, which showed a lytic lesion with a circumferential spiculated sunburst type of periosteal reaction and an ill-defined associated vascular soft tissue component in the proximal third of the meta-diaphysis of the left femur (Fig. 1B). Hypointensity was seen in the radial distribution on gradient echo sequences, corroborating the "sunburst" calcification noted on the radiograph and CT scan (Fig. 1C). The lesion showed significant peripheral enhancement in the soft tissue component (Fig. 1C). The tumor cells were also immunopositive for CK20 and Cdx2, but negative for CK7, confirming metastatic poorly differentiated adenocarcinoma primarily of colonic origin (Fig. 1D). The radiographs showed an ill-defined lytic lesion in the proximal femur that appeared to be an ill-defined lytic area on the PET-CT images and was mildly 18F-fluorodeoxyglucose (FDG)-avid, with a standardized uptake value (SUV) of 3.2 (Fig. 1E).