• Small clusters and single dispersed plasmacytoid cells
• Oval vesicular nuclei, coarse chromatin and moderate nuclear pleomorphism
• Moderate amounts of cytoplasm
• Necrotic background

Commentary: Provisionally, the diagnosis is a high grade carcinoma.

In the salivary gland, the differential diagnoses include:

• Salivary duct carcinoma
• High grade mucoepidermoid carcinoma
• High grade myoepithelial carcinoma
• Adenocarcinoma, NOS
• Metastasis

Distinction of these entities may not be possible based on morphology and the use of immunocytochemistry could further refine the diagnosis. Hence, additional sampling for a cell block should be obtained from the FNA procedure, whenever a clinically aggressive salivary gland lesion is suspected. If further diagnostic characterisation is not possible, the tumour may be signed out as a "high grade carcinoma". Importantly, even if the carcinoma cannot be specifically typed, the high grade nature of the tumour should be conveyed to the clinician so that radical surgery can be planned accordingly.

In the salivary gland, a high grade malignant tumour may arise de novo or due to high grade transformation of a low grade malignancy e.g. adenoid cystic carcinoma or a benign tumour like pleomorphic adenoma. A distinct lower grade / benign component may be present on the smear.

• Degenerate clusters of malignant cells with hyperchromatic nuclei

• Invasive islands of malignant cells with central necrosis
• Moderately pleomorphic vesicular nuclei with prominent nucleoli
• Moderate to abundant eosinophilic cytoplasm

Diagnosis

Salivary duct carcinoma

Take home points

• Marked nuclear atypia and severe nuclear pleomorphism are important features to categorise the tumour as high grade. The grade is important even if the malignancy cannot be specifically typed on cytology, as it may influence the extent of surgery.
• In cytologically high grade malignant tumours, the presence of background necrosis may be a clue to salivary duct carcinoma. 
• Additional material for cell block may be useful to further refine the diagnosis, e.g AR in salivary duct carcinoma.
• Salivary duct carcinomas have some morphologic resemblance to high grade ductal carcinoma of the breast in both cytology and histology samples.