PMC7714602_01
Serous borderline tumor/atypical proliferative serous tumor.
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fig1
The cystic component contained a serous borderline/atypical proliferative tumor (Figure 1) while the solid one appeared to be a high-grade LCNC, which was developed under the serous neoplasm on the cystic wall and comprised 40% of the tumor (stage pT1a/AJCC/2017).
High-grade large cell neuroendocrine carcinoma. High mitotic (yellow circle) and apoptotic (red circle) activity. Extended necrotic areas.
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fig2
Microscopically, the LCNC were characterized by the presence of islands, sheets, and trabeculae with little intervening stroma, cell necrosis, and high mitotic activity (Figure 2).
Positive neuroendocrine markers (chromogranin, synaptophysin, and CD56). High Ki-67 proliferation index.
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fig3
CD56 (cluster of differentiation 56) were partially while synaptophysin ubiquitously expressed in the neuroendocrine cells (Figure 3). CDX-2 (caudal-type homeobox transcription factor 2) and TTF-1 (thyroid transcription factor 1) were negative, as well as inhibin and calretinin.