case_images: PMC11300325_01
case_images: Radiological findings. Plain radiograph (A) showed ossification on the anterolateral thigh (arrow) of the patient, a 4-year-old girl. Computed tomography [(B), coronal view] revealed a heterogeneous soft tissue mass with fat attenuation that included nodular ossifications. MRI revealed a relatively well-defined tumor in the right vastus lateralis muscle, with heterogeneous high intensity on T1- [(C), axial view] and T2-weighted imaging [(D), axial view], heterogeneous high intensity on short tau inversion recovery imaging [(E), coronal view], and heterogenous enhancement on gadolinium-enhanced T1-weighed fat-suppressed imaging [(F), coronal view].
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case_images: Plain radiographs showed ossification on the patient's anterolateral thigh ( Figure 1A ), and computed tomography (CT) revealed a heterogeneous soft tissue mass showing fat attenuation and including multiple nodular ossifications ( Figure 1B ). T1- and T2-weighted imaging but spotty low-intensity lesions that matched with ossifications were identified on T1- and T2-weighted imaging; heterogeneous high intensity on short tau inversion recovery (STIR) imaging was also observed ( Figures 1C-E ). The tumor had heterogeneous enhancement on gadolinium-enhanced T1-weighed fat-suppression imaging ( Figure 1F ).
case_images: Microscopic findings. (A) A low-power view (hematoxylin and eosin [HE] staining, x40) revealed the proliferation of adipocytes, ossification and surrounding fibrosis. (B) A high-power view (HE staining, x100) showed variously sized adipocytes and atypical stromal cells with nuclear atypia in the myxoid stroma. Both the adipocytes and stromal cells were positive for MDM2 (x200) [(C), adipocytes; (D), stromal cells] and CDK4 (x200) [(E), adipocytes; (F), stromal cells].
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case_images: The histopathologic findings were similar to those of the incisional biopsy, with adipocyte proliferation of various sizes, myxoid stroma, and ossification, but nuclear atypia was slightly more prominent in the stromal cells ( Figures 2A, B ). Figures 2C, D ) and cyclin-dependent kinase 4 (CDK4) ( Figures 2E, F ), and negative for pleomorphic adenoma gene 1 (PLAG1). Fluorescence in situ hybridization (FISH) showed abnormal amplification of the MDM2 gene in adipocytes and stromal cells ( Figure 3 ).
case_images: The FISH analysis demonstrated the amplification of the MDM2 gene in both adipocytes (A) and stromal cells (B) (arrows).
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case_images: Figures 2C, D ) and cyclin-dependent kinase 4 (CDK4) ( Figures 2E, F ), and negative for pleomorphic adenoma gene 1 (PLAG1). Fluorescence in situ hybridization (FISH) showed abnormal amplification of the MDM2 gene in adipocytes and stromal cells ( Figure 3 ).