Solid pseudopapillary neoplasm of the pancreas: cytomorphology, pitfalls, and literature review

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare pancreatic neoplasm. Clinically it has non-specific presentations like vague abdominal pain. Imaging studies usually shows a mass at the body or tail of the pancreas. It could be a solid or cystic mass. Distant metastasis is uncommon. Generally, it is considered a tumor with uncertain malignant potential. Overall prognosis is well. Activating somatic mutation of β-catenin gene (CTNNB1) is seen in nearly all cases with SPN. Radical resection is the management of choice and if SPN is unresectable, radiotherapy is the next treatment option. This neoplasm has a unique cytomorphology, immunohistochemistry and prognostically outcome compared with other pancreatic cystic neoplasm. Papillary fronds with fibrovascular core on a cytology smear, combined with a cell-block prepared specimen material that stains with β-catenin is diagnostic for this tumor. The proper cytological evaluation and diagnosis could enable appropriate surgical approach and further management. Since this neoplasm has a good prognosis, it is crucial to diagnose this rare tumor cytologically from other pancreatic tumors by its characteristic cytological features and plan appropriately for the surgical management to improve patient care. In this paper, we comprehensively review SPN and focus on cytomorphologic features, the importance of EUS-guided FNA cytology for diagnosis and management.