Follow-up of indeterminate cytologic diagnoses of solid pancreatic lesions: atypia versus suspicious (one institution's experience)

A comparison of the long-term risk of malignancy between indeterminate cytological diagnoses, namely, atypical versus suspicious for malignancy, from endoscopic ultrasound-guided (EUS) fine-needle aspiration (FNA) of a pancreatic mass has not been well characterized. The primary aim of this study was to compare the risk of malignancy between patients with such indeterminate diagnoses. Secondarily, we investigated whether serologic markers serve as predictors of risk of malignancy in the setting of indeterminate cytological diagnoses.

We reviewed 484 cases of EUS-FNA on solid pancreatic lesions, performed at a single academic tertiary care center from 2004 to 2017. Patients with solid pancreas mass lesions who had atypical or suspicious final cytology were identified for further clinical outcome analysis.

Of the 484 patients with pancreas mass lesions, 53 (11%) were given an indeterminate final cytologic diagnosis, with 28 atypical and 25 suspicious for malignancy. Follow-up was completed for 22 and 20 patients from atypical and suspicious diagnoses, respectively. Of patients with follow-up, 15 (68%) and 18 (90%) had subsequent diagnoses of malignancy from atypical and suspicious groups, respectively. There was no statistical difference in predicting risk of malignancy between the two groups (P = 0.24). Serologic markers were available in 29 of 42 patients with follow-up. Serologic markers were elevated in 21 of 29 patients and all were subsequently diagnosed with malignancy. Elevated serologic markers correlated with future risk of malignancy (P = 0.0026).

The risk of subsequent malignancy is high for both atypical and suspicious pancreatic solid lesions but there exists no statistical difference between the two. Combined serologic markers with indeterminate cytology proved to be a good predictor of malignancy.