The new guidelines of Papanicolaou Society of Cytopathology for respiratory specimens: Assessment of risk of malignancy and diagnostic yield in different cytological modalities

Background: In 2016, the Papanicolaou Society of Cytopathology (PSC) issued a new classification scheme for respiratory cytology. We aim to evaluate our samples according to this classification and to assess risk of malignancy and diagnostic yield of different cytological modalities.

Methods: Respiratory specimens (sputum, bronchial wash/brush, BAL and FNA) obtained between 2007 and 2016 were reclassified according to PSC guidelines. Risk of malignancy for each diagnostic category was determined. Diagnostic yield was evaluated based on three-categorical approach.

Results: One thousand, two hundred and ninety respiratory specimens were retrieved, of which 280 had histologic follow-up. Samples were reclassified as nondiagnostic 16%, negative for malignancy 53%, atypical 5.4%, neoplastic (benign neoplasm/low-grade carcinoma) 0.4%, suspicious for malignancy 2.1% and malignant 23.1%. Risk of malignancy for each category was 64.01% for ND, 48.27% for NM, 59.09% for A, 100% for N-B-LG; 90% for SM and 89.74% for M. When only malignant cases were considered positive tests, cytology sensitivity was 55% and specificity 88%.

Conclusion: Our results were in line with PSC guidelines, but the use of multiple cytological techniques may cause some discrepancies in overall diagnostic yield and in estimated risks of malignancy, which is important due to the widespread utilization of different cytological procedures.