Solid Pseudopapillary Neoplasm of the Pancreas with High-Grade Malignant Transformation Involving p16-RB Pathway Alterations

Figure 3

Histological and immunohistochemical findings of high-grade undifferentiated areas of the pancreatic tumour (×400). (a) Nested-to-diffuse growth of more poorly cohesive monomorphic cells with increased nuclear atypia. Mitoses were conspicuous (indicated by red circles). (b) Nuclear and cytoplasmic immunohistochemical expression of β-catenin. (c) Ki-67 index: 22%. (d) Diffuse RB protein loss. (e) Diffuse p16 protein overexpression.

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