Cytohistological diagnosis of pancreatic serous cystadenoma: a multimodal approach

Aims Serous cystadenomata (SCAs) are benign pancreatic cystic neoplasms that present a diagnostic challenge despite many investigational approaches. Notwithstanding the promise of molecular diagnostics, these tests have limited accessibility in day-to-day surgical pathology practices. We aim to corroborate and build on recent evidence which suggests that positive alpha-inhibin immunohistochemistry (IHC) is a helpful adjunct in the biopsy confirmation of pancreatic SCA. Methods We retrospectively reviewed 22 fine-needle aspirates/biopsies from 14 patients (mean age 65 years, 47-83 years) with pancreatic multicystic lesions radiologically suspicious for SCA (location: 6 body, 2 head, 4 tail, 1 neck, 1 uncinate; cyst size: mean 3.7 cm, 2.0-7.6 cm), as well as an additional 10 pancreatic resection specimens with confirmed SCA; alpha-inhibin IHC was performed on all cell blocks, biopsy slides and representative resection specimen sections. Where available, associated cyst fluid was analysed for correlative vascular endothelial growth factor A (VEGF-A) and carcinoembryonic antigen levels. Results An alpha-inhibin IHC sensitivity of 80% was observed in the cases with resection confirmed SCA. Of the fine-needle aspirate/biopsy specimens, 59% (13/22) contained epithelial cells strongly positive for alpha-inhibin. When selecting for specimens that exhibited distinct strips of epithelium, the alpha-inhibin strong positivity rate increased to 73% (8/11). VEGF-A values were supportive of false-negative alpha-inhibin IHC in three cases and true-negative alpha-inhibin IHC in one case. Conclusion This study postulates a diagnostic algorithm to confirm pancreatic SCA which may help to decrease unnecessary follow-up endoscopy/surgical resection and would decrease the associated morbidity, mortality and financial costs in patients with this otherwise benign condition.