PMC5043404_01
A-B Computed tomography (CT) scan "arterial phase" showed a hypervascularity and slow wash-out. B-C Computed tomography (CT) scan showed a 2.5 cm solid nodule located in the uncinate process of the pancreas.
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The lesion was further studied by contrast enhancement ultrasound (CEUS) and computed tomography (CT) scan (Fig. 1A and B). Arterial phase hypervascularity and slow wash-out were observed (Fig. 1C and D), leading to the hypothesis of a neuroendocrine pancreatic tumor (NET), which was further confirmed by a subsequent In-Pentetreotide Scan examination.
A (H&E, 4x) - Hematoxylin and eosin staining showing well circumscribed tumor with numerous blood vessels. B (H&E, 40x) - The tumor cells are arranged in nests ("Zellballen") bound by sostentacular cell and fibrovascular stroma. Nuclear atypia is common and is not an expression of malignancy. C (synaptophysin, 10x) - Immunohistochemistry of the "Zellballen" neoplastic cells demonstrates positivity for synaptophysin; the normal pancreas is negative. D (CAM 5.2, 20x) - Immunohistochemistry showed negative staining in neoplastic cells for cytokeratin (CAM5.2) and positive staining in non-neoplastic pancreatic cells.
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Microscopically, the lesion was organized in nests of variable dimensions, with numerous blood vessels and hemorrhagic areas (Fig. 2a). The nuclei were pleomorphic, sometimes very large, and the cytoplasms abundant, finely granular and eosinophilic (Fig. 2b). Strong immunohistochemical positivity for chromogranin A and synaptophysin was observed (Fig. 2c), as well as focal positivity for S100 and somatostatin, while cytokeratins (CAM 5.2) (Fig. 2d) and AE1/AE3 were negative.