Oncocytic Salivary Gland Tumours: Cytological Features and Diagnostic Pitfalls

Oncocytes are epithelial cells having abundant eosinophilic cytoplasm. The presence of oncocytes in salivary glands pose a diagnostic challenge since they can be present in lesions ranging from non-neoplastic, benign to malignant. FNAC is a simple procedure which can aid in the pre-operative diagnosis of these lesions. This study is an eight year retrospective study in which salivary gland aspiration cytology cases having oncocytic cells and with available corresponding histopathology were included. These slides were reviewed for features like cellularity, presence of oncocytic cells, glandular elements, squamoid cells, nuclear atypia, mitosis, lymphoid tissue, necrosis. Twenty cases were included in the study. The mean age of presentation was 60 years showing male preponderance with parotid gland being the most common site of involvement. Concordant diagnosis on cytology and histopathology was seen in 16 cases and discordance was seen in 4 cases. All the discordant cases were reported as benign on cytology but on histopathology they were labelled as acinic cell carcinoma, squamous cell carcinoma, mucoepidermoid carcinoma and an intraparotid lymph node respectively. Review of discordant cases showed subtle findings like ill-formed acini, cytoplasmic vacuolation, goblet cells and dysplastic foci raising suspicion of a different diagnosis. The potential areas of pitfall and cause of discrepancy have been discussed in this study. It is crucial to be aware of the spectrum of lesions in which oncocytes are seen, to enable an accurate diagnosis on cytology. Careful evaluation of smears for subtle clues can minimize errors.