A 22-year-old woman has a well-circumscribed 7 cm solid-cystic mass in the pancreatic tail with areas of hemorrhagic degeneration. Biopsy shows monomorphic sheets of cells around delicate capillaries with nuclei oriented away from vessels, and scattered grooved nuclei. Immunohistochemistry demonstrates strong nuclear and cytoplasmic beta-catenin staining along with CD10 positivity. The most likely diagnosis is:

• A Acinar cell carcinoma
• B Well-differentiated pancreatic neuroendocrine tumor
• C Solid pseudopapillary neoplasm ✓
• D Pancreatoblastoma

Explanation

Solid pseudopapillary neoplasm occurs almost exclusively in young women, typically in the pancreatic tail, and shows hemorrhagic degeneration creating the pseudopapillary pattern where cells detach from capillaries. Aberrant nuclear beta-catenin expression from CTNNB1 mutation is the defining immunohistochemical finding, with CD10 and synaptophysin often positive. Neuroendocrine tumors show chromogranin and diffuse endocrine markers without nuclear beta-catenin, while acinar cell carcinoma expresses trypsin and BCL10.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.