case_images: PMC6287168_01
case_images: Computed tomography (CT): coronal (a), sagittal (b), and axial views (c) of the left knee, July 2009.
case_images: CRIPA2018-4160925.001.jpg
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case_images: fig1
case_images: Computed tomography (CT) revealed a mixed radiolucent and sclerotic permeative lesion within the left posterior medial epiphysis with medial cortical destruction (Figure 1).
case_images: Magnetic resonance images (MRI): T1 coronal, sagittal, and axial views (a, b, c), STIR coronal (d), T2 sagittal (e), and axial views (f) of the left knee, July 2009.
case_images: CRIPA2018-4160925.002.jpg
case_images: PMC6287168_01_CRIPA2018-4160925.002.jpg
case_images: fig2
case_images: T1 and bright on STIR and T2 weighted images (Figure 2). The radiographic differential diagnosis included chondroblastoma, osteomyelitis and eosinophilic granuloma.
case_images: Three-phase bone scintigraphy, August 2009. Increased uptake in the distal left femur on delayed images.
case_images: CRIPA2018-4160925.003.jpg
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case_images: fig3
case_images: Fludeoxyglucose-positron emission tomography (FDG-PET), August 2009. Increased activity of FDG within the left knee (SUV max of 17.11), with physiologic distribution of FDG in the remainder of the body.
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case_images: fig4
case_images: Anteroposterior (a) and lateral radiographs (b) of the left knee after core biopsy, September 2009.
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case_images: fig5
case_images: Fluoroscopic guided core biopsy was performed (Figure 5).
case_images: High power magnification, hematoxylin and eosin (H&E) staining. Sheets of dyscohesive atypical cells with large hyperchromatic round nuclei and scant cytoplasm.
case_images: CRIPA2018-4160925.006.jpg
case_images: PMC6287168_01_CRIPA2018-4160925.006.jpg
case_images: fig6
case_images: Histologic analysis revealed a round cell tumor (Figure 6).
case_images: Immunohistochemistry staining. CD20 and CD79a: Strong positive cytoplasmic staining indicative of lymphoid cells of B-type lineage (a, b). CD3: scant scattered reactive T-cells in background (c).
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case_images: PMC6287168_01_CRIPA2018-4160925.007.jpg
case_images: fig7
case_images: Immunohistochemistry was positive for CD20 and CD79a, confirming diffuse large B-cell lymphoma (Figure 7).