Which immunohistochemical finding is characteristic of solid pseudopapillary neoplasm of the pancreas?

• A Diffuse chromogranin and synaptophysin positivity
• B Membranous CD117 positivity
• C Loss of SMAD4 expression
• D Strong nuclear accumulation of beta-catenin ✓

Explanation

Solid pseudopapillary neoplasm harbors activating mutations of CTNNB1, the gene encoding beta-catenin, producing abnormal nuclear accumulation of beta-catenin on immunohistochemistry, a hallmark diagnostic feature. These tumors arise almost exclusively in adolescent girls and young women and behave indolently despite their size. Diffuse chromogranin and synaptophysin positivity indicates neuroendocrine differentiation, CD117 positivity suggests gastrointestinal stromal tumor, and SMAD4 loss is characteristic of ductal adenocarcinoma, not this entity.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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