A 22-year-old woman has a 9 cm solid and cystic pancreatic body mass. Biopsy shows uniform cells arranged around hyalinized, blood-filled spaces with focal pseudopapillae. Immunohistochemistry demonstrates strong nuclear accumulation of beta-catenin. What is the diagnosis?

• A Pancreatic neuroendocrine tumor
• B Acinar cell carcinoma
• C Serous cystadenoma with degenerative change
• D Solid pseudopapillary neoplasm ✓

Explanation

Solid pseudopapillary neoplasm occurs almost exclusively in young women, forms large well-circumscribed masses, and shows monomorphic cells around hyalinized vascular cores producing pseudopapillae. Abnormal nuclear beta-catenin accumulation from altered Wnt signaling is characteristic and distinguishes it from neuroendocrine tumors, which express chromogranin and synaptophysin. It is a low-grade malignant neoplasm cured by complete excision. Acinar cell carcinoma affects older adults and stains for trypsin and chymotrypsin.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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