Cytologic Categorization with Risk Stratification of Endoscopic Ultrasound-Guided Fine Needle Aspiration from Pancreatic Lesions Based on Guidelines of the Papanicolaou Society of Cytopathology: 12-Year Tertiary Care Experience

Abstract

Background and aims: Pancreatic malignancy is an important cause of cancer mortality worldwide. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) plays a crucial role in the pre-operative diagnosis of pancreatic lesions. In this study, we have analyzed the cytological spectrum of pancreatic lesions in the Indian population over 12 years, categorized them according to the Papanicolaou Society of Cytopathology System for Reporting Pancreaticobiliary Cytology (PSCPC), and assessed the risk of malignancy (ROM) for each of the categories.

Methods: A computerized data search from January 2008 to December 2019 revealed 581 pancreatic EUS-FNA samples, among which surgical follow-up was available for 73 cases. All cytological specimens were reviewed and prospectively classified into one of the six diagnostic categories proposed by the PSCPC. Subsequently, a cytohistological correlation was performed and the ROM was calculated for each category.

Results: The cytologic diagnoses included 50 nondiagnostic (category I), 175 negative for malignancy (category II), 19 atypical (category III), 27 neoplastic:benign (category IVA), 30 neoplastic:other (category IVB), 26 suspicious (category V), and 254 malignant (category VI) cases. ROM for non-diagnostic aspirates, nonneoplastic benign specimens, atypical cases, neoplastic:benign, neoplastic:other, suspicious for malignancy, and the malignant category was 16.7%, 7.1%, 33.3%, 0.0%, 20.0%, 100%, and 78.6%, respectively.

Conclusion: We document an increased risk of malignancy from category I to category VI of the PSCPC. The malignancy risk for category VI (malignant) was statistically significant in our study but was lower in comparison to the values reported by other authors. Nonetheless, such an approach would establish transparent communication between the pathologist and the clinician, as well as aid the clinician in decision making, particularly in intermediate categories.

Keywords: EUS-FNA; Papanicolaou Society of Cytopathology; pancreas; risk of malignancy; risk stratification..

Figure 1. Cytological spectrum of pancreatic lesions

A. Chronic pancreatitis: Benign pancreatic ductal epithelial cells with mild anisonucleosis embedded in hemorrhagic background (Giemsa; x400 magnification); B. Pancreatic Tuberculosis:Clusters of epithelioid histiocytes admixed with lymphocytes and necrosis (Giemsa; x400 magnification), inset: positive for acid-fast bacilli (Ziehl-Neelsen stain); C. Mucinous cystic neoplasm: Occasional benign epithelial cells on a mucinous background (Giemsa; x400 magnification); D. Suspicious for malignancy: Cluster of atypical epithelial cells with pleomorphic hyperchromatic nuclei (Giemsa; x400 magnification)

Figure 2. Cytological spectrum of pancreatic lesions

A. Neuroendocrine tumour: Monomorphic tumour cells with stippled nuclear chromatin and scant cytoplasm (Giemsa; x400 magnification); B. Solid pseudo-papillary neoplasm: Dispersed population of round to oval cells with mildly pleomorphic hyperchromatic nuclei and nuclear grooving (Giemsa; x400 magnification); C. Well-differentiated adenocarcinoma: Acinar arrangement of tumour cells with nuclear pleomorphism (Giemsa; x400 magnification), inset: intracytoplasmic mucin globule (Periodic-acid Schiff stain after diastase predigestion); D. Metastatic adenocarcinoma (Giemsa; x400 magnification).

Figure 3. Cytological spectrum of pancreatic lesions

A. Adenosquamous carcinoma: Three-dimensional cluster of tumour cells with interspersed dyskeratotic cells on a necrotic background (Pap; x400 magnification). B. Mucinous cystadenocarcinoma: Cluster of tumour cells on abundant extracellular pool of mucin (Giemsa; x400 magnification). C. Undifferentiated carcinoma: Loosely cohesive tumour cells with marked nuclear pleomorphism and multinucleation (Giemsa; x400 magnification). D. Non-Hodgkin lymphoma: Small to medium-sized atypical lymphoid cells with lymphoglandular bodies (Giemsa; x400 magnification).

Figure 4. Non-neoplastic elements in pancreatic cytology

A. Honeycomb pattern of normal duodenal mucosa with adjoining benign pancreatic acini (Giemsa; x200 magnification). B. Goblet cell (arrow)(Giemsa; x400 magnification). C. Picket-fence arrangement with basally located nuclei of normal duodenal epithelial cells (Giemsa; x400 magnification). D. Clusters of benign pancreatic acini admixed with hemosiderin-laden macrophages on a hemorrhagic background (Giemsa; x400 magnification).