PMC7232720_01
Abdominal CT showing cystic lesion in the spleen of 40 mm diameter.
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A control 18F-FDG PET/CT at 6 months showed the lung without evidence of disease, and the splenic lesion grew to a diameter greater than 40 mm; it was observed without metabolic activity (Figure 1).
PET/CT images show a 40 mm lesion without increased metabolic activity.
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Due to the increment of size and risk of spontaneous rupture, it was decided to perform splenectomy (Figure 2).
Pathology macroscopic picture shows the spleen with a cystic lesion of 5.5 cm.
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Pathology reported a 5.5 x 5.5 x 4 cm semi ovoid tumour, cystic-looking lesion, with serous content, wall cut 0.2 cm, with simple papillary formations (Figure 3).
(a) Ovoid splenic lesion of cystic appearance, 5.5 cm major axis on the wall. (b) Papillary projections are observed. (c) Photomicrograph in which simple papillae protruding from the cyst wall (haematoxylin and eosin, 4x) are observed. (d). At a higher magnification, cuboidal cells with clear nuclei and bars, characteristic of papillary thyroid carcinoma (haematoxylin and eosin, 20x) are observed.
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In sections with haematoxylin and eosin staining, the neoplastic proliferation cyst is with a papillary growth pattern, and cuboidal cells, nuclear pleomorphism, empty nuclei and abundant nuclear bars are without mitosis (Figure 4).
Photomicrographs of the immunohistochemical study performed on the splenic lesion. (a) PAX8 diffuse nuclear positive. (b) Diffuse cytoplasmic positive thyroglobulin. (c) TTF-1 diffuse nuclear positive. (d) CK19 diffuse cytoplasmic positive.
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TTF-1 diffuse nuclear positive, PAX8 diffuse nuclear positive, and CK5/6 negative were observed (Figure 5). The diagnosis was papillary thyroid carcinoma with a cystic pattern, of conventional type, well differentiated, with focal microcalcification and intraluminal xanthomatous response, without extracapsular extension.