case_images: PMC7817810_01
case_images: Radiological images of the pelvis. Axial CT (A, bone window) showed an aggressive lytic lesion involving the left femoral neck and trochanteric region associated with cortical destruction and limited periosteal reaction. A coronal fat-saturated T2-weighted MRI image of the pelvis (B) demonstrated a heterogeneously high signal lesion in the left proximal femur that was limited in the medullary cavity without extraosseous extension. Meanwhile, MRI images (C) showed a hyperintense soft tissue mass in the dorsal side of the penis with poorly defined zones of high signal in the corpus cavernosum around the tumor.
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case_images: PMC7817810_01_fped-08-591257-g0001.jpg
case_images: F1
case_images: Computed tomography showed an aggressive lytic lesion involving the left femoral neck and trochanteric region with cortical destruction and limited periosteal reaction (Figure 1). Meanwhile, MRI images demonstrated a hyperintense lesion measuring approximately 5.1 cm x 2.6 cm x 2.0 cm on the dorsal side of the penis, with poorly defined zones of high signal in the corpus cavernosum around the tumor (Figure 1).
case_images: The FDG PET/CT scan of the whole body. A PET-CT scan showed increased fluorodeoxyglucose uptake in the lesions of the penis and corpus cavernosum
  (A,B). Multiple lesions with uptake were detected in the bilateral lungs, ribs, left proximal femur, lumbar vertebrae, and the left acetabulum and sacrum, indicating the possibility of metastatic disease (C-H).
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case_images: PMC7817810_01_fped-08-591257-g0002.jpg
case_images: F2
case_images: SUV values of 6.7 and 8.2, respectively (Figure 2); multiple lesions with mild uptake were also found in the bilateral lungs, ribs, lumbar vertebrae, acetabula, and sacra, indicating the presence of metastatic disease (Figure 2). Subsequently, an incisional biopsy of the penis was performed, and the pathological findings microscopically revealed small undifferentiated round cell tumors with monomorphic cytomorphology, round-oval nuclei (Figure 3).
case_images: Pathological features of the penile lesion. (A) The H and E stain showed that the tumor is composed of uniform small round cells (magnification 400 x). The immunohistochemical stain showed (B) Diffuse membranous CD99 positivity and focal FLI1 positivity (C) (magnification 400 x). FISH molecular analysis demonstrated the EWS gene translocation (D).
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case_images: PMC7817810_01_fped-08-591257-g0003.jpg
case_images: F3
case_images: SUV values of 6.7 and 8.2, respectively (Figure 2); multiple lesions with mild uptake were also found in the bilateral lungs, ribs, lumbar vertebrae, acetabula, and sacra, indicating the presence of metastatic disease (Figure 2). Subsequently, an incisional biopsy of the penis was performed, and the pathological findings microscopically revealed small undifferentiated round cell tumors with monomorphic cytomorphology, round-oval nuclei (Figure 3). The fluorescence in situ hybridization (FISH) identified the translocation of EWS gene, consequently confirming the diagnosis of Ewing sarcoma (Figure 3).