case_images: PMC9989303_01
case_images: Transvaginal ultrasound evaluation of uterus and adnexa. Uniform endometrium (A) and right and left ovaries of normal appearance (B, C).
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case_images: Ultrasound examination performed at gynecologic oncology center by experienced sonographer revealed normal gynecologic findings of the uterus and adnexa, smooth peritoneum, small amount of free fluid, and neither adhesions in the pelvis nor other signs related to endometriosis ( Figure 1 ). Lateral to the right ovary, there were three bulky lymph nodes detected in the right obturator fossa, which were misinterpreted by the referring physician as endometrioma ( Figure 2  and  Videoclip 1 ). Expert sonographer detected two inhomogeneous lesions of 24 and 25 mm in the segment 4b of liver parenchyma, considered to be metastatic spread on gray scale ultrasound ( Supplementary Figure S1  and  Videoclip 2 ). The PET-CT showed metabolic accumulation of 18F-fluorodeoxyglucose (18F-FDG) in the right obturator fossa ( Figure 3 ) but no other metabolically active lesions in the body including the liver ( Supplementary Figure S1 ). On MRI, the liver lesions showed enhancement in the early stage with persistence to late stage suggesting the lesions to be more likely adenoma or focal nodular hyperplasia ( Supplementary Figure S1 ). In  Supplementary Figure S4 , positive expression of CK7 and HNF1beta were demonstrated.
case_images: Ultrasound and power Doppler imaging of infiltrated lymph nodes in the right obturator fossa. Transvaginal ultrasound imaging demonstrates three bulky lymph nodes: first iliac lymph node (29 x 26 x 31 mm) infiltrated by tumor nodules located in the close proximity to the right ovary (arrow) (A) with visible transcapsular vessels penetrating the lymph node from the outside (arrows) and ring-shaped vessels marked with white circles (D). Second iliac lymph node (25 x 13 x 21 mm) was lateral to the first one, infiltrating the pelvic side wall and internal iliac vessels up to the interiliac bifurcation with infiltration of the external iliac vein (B), this lymph node was less vascularized on color Doppler images (E). Third infiltrated node (26 x 13 x 30 mm) was located deeper in the pelvis, near the right lateral parametrium (C), with transcapsular vessels on color Doppler image (F) See also 
  Videoclip 1
  .
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case_images: Lateral to the right ovary, there were three bulky lymph nodes detected in the right obturator fossa, which were misinterpreted by the referring physician as endometrioma ( Figure 2  and  Videoclip 1 ). Expert sonographer detected two inhomogeneous lesions of 24 and 25 mm in the segment 4b of liver parenchyma, considered to be metastatic spread on gray scale ultrasound ( Supplementary Figure S1  and  Videoclip 2 ). To briefly describe ultrasound-guided tru-cut biopsy using a transvaginal approach, no patient preparation, fasting, or routine administration of analgesics or antibiotics is required for this minimally invasive approach in the outpatient setting ( Supplementary Figure S2  and  Videoclip 3 ).
case_images: Axial fused PET-CT showed increased accumulation of 18F-FDG in the bulky iliac lymph nodes on the right obturator fossa of up to 36 x 25 mm (A, C), morphologic images from CECT demonstrating enlarged nodes in the right obturator fossa (white arrows) (B, D). PET-CT (positron emission tomography combined with computed tomography), CECT (contrast enhanced computed tomography), and 18F-FDG (18F- fluorodeoxyglucose).
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case_images: To briefly describe ultrasound-guided tru-cut biopsy using a transvaginal approach, no patient preparation, fasting, or routine administration of analgesics or antibiotics is required for this minimally invasive approach in the outpatient setting ( Supplementary Figure S2  and  Videoclip 3 ). The PET-CT showed metabolic accumulation of 18F-fluorodeoxyglucose (18F-FDG) in the right obturator fossa ( Figure 3 ) but no other metabolically active lesions in the body including the liver ( Supplementary Figure S1 ). Tru-cut biopsy revealed a poorly differentiated tumor composed of solid sheets of polygonal eosinophilic cells with marked nuclear pleomorphism, conspicuous mitotic activity, and necrotic areas ( Supplementary Figure S3 ).
case_images: Ultrasound and final histological demonstration of infiltrated lymph node. Non-infiltrated residual cortex on the ultrasound and histological imaging of lymph node marked with yellow circles (A, B), with intranodal involvement due to solid sheets of poorly differentiated extensively necrotic carcinoma marked with white circles on specimen (B) and white asterisks on ultrasound images (C, E) and on the specimen (D); on Power Doppler imaging infiltrated nodules reveal a ring-shaped vascularization (yellow circles) in (E); arrows indicate intact lymph node capsule (F). See also 
  Videoclip 4
  .
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case_images: In  Supplementary Figure S4 , positive expression of CK7 and HNF1beta were demonstrated. The three infiltrated lymph nodes in the right obturator fossa were confirmed to have extensive involvement by poorly differentiated cancer ( Figure 4 ) with loss of MSH2 and MSH6 protein expression.