case_images: PMC11390348_01
case_images: (A) CT imaging of the lesions (coronal plane).The abdominal mass was huge with inhomogeneous density and uneven enhancement. (B) MRI imaging of the lesions (sagittal plane). The MRI revealed a large cystic and solid lesion in the pelvic and abdominal cavity, internally segmented by multiple septa, with approximate dimensions of 11.7cm x 8.7cm x 19.1cm. (C) T1-weighted image (T1WI). The T1-weighted image (T1WI) showed heterogeneous slightly high signal intensity, accompanied by patchy areas of low signal intensity. (D) T2-weighted image (T2WI). The T2-weighted image (T2WI) exhibited heterogeneous slightly high signal intensity, with patchy low signal areas. (E) Diffusion-weighted imaging (DWI). Diffusion-weighted imaging (DWI) revealed patchy areas of high signal intensity. (F) Apparent diffusion coefficient (ADC). The apparent diffusion coefficient (ADC) demonstrated regions of low signal intensity.
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case_images: A computed tomography (CT) scan revealed the presence of an abdominal mass ( Figure 1A ). The magnetic resonance imaging (MRI) revealed a large cystic and solid lesion in the pelvic and abdominal cavity, internally segmented by multiple septa, with approximate dimensions of 11.7cm x 8.7cm x 19.1cm ( Figure 1B ). The T1-weighted image (T1WI) showed heterogeneous slightly high signal intensity, accompanied by patchy areas of low signal intensity ( Figure 1C ). Meanwhile, the T2-weighted image (T2WI) exhibited heterogeneous slightly high signal intensity, with patchy low signal areas ( Figure 1D ). Diffusion-weighted imaging(DWI) revealed patchy areas of high signal intensity ( Figure 1E ), while the apparent diffusion coefficient(ADC) demonstrated regions of low signal intensity ( Figure 1F ). Complete timeline of the events is shown in  Supplementary Figure 1 .
case_images: Postoperative photograph of the resected tumor. Lymphatic tissue encompassing the abdominal aorta, iliac arteries, and sacral region was resected along with excision of the greater omentum. To avoid catastrophic risks, the tumor capsule adhering to the surface of the abdominal aorta and bilateral iliac arteries was not resected.
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case_images: To avoid catastrophic risks, the tumor capsule adhering to the surface of the abdominal aorta and bilateral iliac arteries was not resected ( Figure 2 ).
case_images: (A) Histological sections of patient's tumor [H&E; x200]. The tumor cells are oval in shape, with obvious nucleoli and significant melanin granule deposition. (B) Positive immunoactivity for MelanA (x100). (C) Positive immunoactivity for HMB45 (x100). (D) Positive immunoactivity for S-100 (x100). (E) Positive immunoactivity for SOX10 (x100). (F) Ki67 immunostain with a proliferative index of 2% (x200).
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case_images: Figure 3 ). For example, HMB45, Melan-A, SOX10, S-100, and CD117 showed positive results.