case_images: PMC6759322_01
case_images: CT scan showing extensive dirty thickening of the peritoneum, fatty stranding and ascites accumulation in the abdomen cavity.
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case_images: figure1
case_images: A computed tomography (CT) disclosed ascites accumulation in addition to dirty thickening and heterogeneous fat stranding of peritoneum and mesentery (Figure 1).
case_images: PET/CT scan showing diffuse uptake over peritoneal space (SUVmax from 5.6 to 6.4).
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case_images: figure2
case_images: Much to his surprise and embarrassment, besides the predicted high uptake in the abdomen cavity (Figure 2), a 1.8-cm moderate uptake lesion over right lower buccal area appeared along with what presumed to be metastatic spots over right neck lymph nodes and vertebral bodies (Figure 3).
case_images: PET/CT scan. (A) A 1.8-cm lesion with moderate uptake over right lower buccal/gingival area with an avid metastatic lesion over spine. (B and C) Lymph node metastases over right neck.
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case_images: figure3
case_images: Much to his surprise and embarrassment, besides the predicted high uptake in the abdomen cavity (Figure 2), a 1.8-cm moderate uptake lesion over right lower buccal area appeared along with what presumed to be metastatic spots over right neck lymph nodes and vertebral bodies (Figure 3).
case_images: Squamous cell carcinoma of right lower buccal mucosa within oral cavity (haematoxylin and eosin stain). (A) Keratinizing large-sized polygonal tumour cells with abundant glassy/eosinophilic cytoplasm and pleomorphic nuclei, arranged in solid nests (x200). (B) Prominent acantholytic change in certain areas (x400).
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case_images: figure4
case_images: A 2.5-cm right lower buccal ulcer with exophytic mass was subsequently disclosed by the oral surgeon and an incision biopsy led to a diagnosis of keratinizing squamous cell carcinoma (Figure 4).
case_images: Metastatic squamous cell carcinoma over peritoneum (hematoxylin and eosin stain). (A) Neoplastic cells bearing high nucleus/cytoplasm ratio, pleomorphic nuclei and occasional nucleoli forming focal squamoid nests (x200). (B) Acantholytic change similar to that seen in buccal carcinoma specimen, resulting in glandular pattern with some detached or apoptotic tumour cells in the lumen-like structure (x400).
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case_images: figure5
case_images: Later on, careful investigation of the peritoneal tumour let the pathologist decide that it was most likely also a squamous cell carcinoma with focal squamoid nests and severe acantholytic change very similar to the oral cavity lesion (Figure 5).
case_images: Metastatic squamous cell carcinoma over peritoneum. Negative immunohistochemical staining for (A) CK7, (B) CK20 and (C) TTF-1. (D) Negative histochemical staining for mucicarmine.
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case_images: The tumour cells were negative for cytokeratin 7 (CK7), cytokeratin 20 (CK20), thyroid transcription factor-1 (TTF-1) and muscarmine (Figure 6) but positive for cytokeratin 5/6 (CK5/6) and p40 (Figure 7) in histochemistry and immunohistochemistry studies.
case_images: Metastatic squamous cell carcinoma over peritoneum. Positive immunohistochemical staining for (A) CK5/6 and (B) p40.
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case_images: figure7
case_images: The tumour cells were negative for cytokeratin 7 (CK7), cytokeratin 20 (CK20), thyroid transcription factor-1 (TTF-1) and muscarmine (Figure 6) but positive for cytokeratin 5/6 (CK5/6) and p40 (Figure 7) in histochemistry and immunohistochemistry studies.
case_images: Metastatic squamous cell carcinoma over peritoneum. Negative immunohistochemical staining for (A) calretinin, (B) WT1, (C) HBME-1 and (D) D2-40.
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case_images: figure8
case_images: The possibility of a primary peritoneal mesothelioma could be excluded based on the negative immunohistochemical staining results for calretinin, Wilms' tumour 1 (WT1), Hector Battifora mesothelial-1 (HBME-1) and podoplanin (D2-40) (Figure 8).
case_images: Negative immunohistochemical staining for (A, B) TNFalpha and (C, D) CD24 in (A and C) primary buccal squamous cell carcinoma and (B and D) metastatic squamous cell carcinoma over peritoneum.
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case_images: figure9
case_images: Tumour cells from both the primary site and the peritoneum turned out to be negative for tumour necrosis factor alpha (TNFalpha) and CD24 (Figure 9), but positive for CD44 and CD36 (Figure 10).
case_images: Positive immunohistochemical staining for (A, B) CD44 and(C, D) CD36 in (A and C) primary buccal squamous cell carcinoma and (B and D) metastatic squamous cell carcinoma over peritoneum.
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case_images: figure10
case_images: Tumour cells from both the primary site and the peritoneum turned out to be negative for tumour necrosis factor alpha (TNFalpha) and CD24 (Figure 9), but positive for CD44 and CD36 (Figure 10).