case_images: PMC9411663_01
case_images: Ultrasound and CT scan of subcutaneous soft tissue metastases (A-D). (A) Ultrasound scan of subcutaneous soft tissue metastasis in the left upper quadrant of the abdomen. (B) Ultrasound scan of subcutaneous soft tissue metastasis in the left posterior thorax. (C) CT scan of subcutaneous soft tissue metastasis in the left upper quadrant of the abdomen (red arrow). (D) CT scan of subcutaneous soft tissue metastasis in the left posterior thorax (red arrow).
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case_images: An ultrasound scan demonstrated a 1.8x1.0x1.3 cm lesion along the left upper quadrant of the abdomen and a 1.9x1.2x1.5 cm lesion in the left posterior thorax ( Figures 1A, B ). A CT scan confirmed the ultrasound diagnosis ( Figures 1C, D ) and showed a new finding of multiple lung metastases.
case_images: Biopsy of subcutaneous soft tissue metastasis in the left upper quadrant of the abdomen. (A-D). (A) Squamous cell carcinoma is observed, which infiltrates the adipose tissue. Atypical epithelioid cells are observed in fibro tissue, muscle tissue and adipose tissue. (hematoxylin and eosin, original magnification x 200). (B) Positive CK5/6 immunohistochemical staining in a membranous distribution on the tumor cells (brown) (hematoxylin and eosin, original magnification x 200). (C) Positive P40 immunohistochemical staining (brown) (hematoxylin and eosin, original magnification x 200). (D) Positive synaptophysin immunohistochemical staining in a membranous distribution on the tumor cells (brown) (hematoxylin and eosin, original magnification x 200).
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case_images: On excision biopsy, the subcutaneous mass of the left abdomen proved to be metastatic ESCC ( Figure 2A ). The tumor cells were immunohistochemically positive for CK5/6 and P40, compatible with squamous cell carcinoma ( Figures 2B, C ). Moreover, the tumor cells were also positive for synaptophysin, which indicated neuroendocrine differentiation ( Figure 2D ).
case_images: PET/CT scan of subcutaneous soft tissue metastasis in the left posterior thorax. (A, B). (A) Maximum intensity projection (MIP) image of the whole body demonstrates a large FDG avid nodule in the left thorax (red arrow). (B) Fused PET/CT and CT axial image demonstrates a large FDG avid nodule in the left posterior thorax (SUVmax=20.3) (red arrow).
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case_images: In addition, an intensely hypermetabolic lesion was localized in the left posterior thorax (SUVmax=20.3) (  Figures 3A, B  ).