• Epithelial cells arranged in small clusters, papilliform structures and single cells
• Enlarged nuclei and moderate nuclear pleomorphism
• Prominent nucleoli
• Abundant wispy cytoplasm
• Background necrosis
• No matrix or mucoid material seen

The cytomorphology is that of a high grade carcinoma and these entities may be morphologically indistinguishable:

⁃ Salivary duct carcinoma
⁃ High-grade mucoepidermoid carcinoma
⁃ Adenocarcinoma, NOS
⁃ Metastatic adenocarcinoma

It is helpful to look for the presence of a low-grade component to suggest high grade transformation (e.g. carcinoma ex pleomorphic adenoma). 

A cell block was available, showing sparse lesional cells. In view of the presence of high grade features and background necrosis, salivary duct carcinoma was suspected, and immunocytochemistry was performed: 

Immunocytochemistry: The tumour cells are positive for GATA3 and AR.

A complete resection was performed. Here are the histology pictures: 

Histology shows islands of tumour cells with high nuclear grade, abundant eosinophilia cytoplasm and surrounding central comedonecrosis. A diagnosis of salivary duct carcinoma was made. 

Malignant (Milan system, category VI)

High grade carcinoma, with features suggestive of salivary duct carcinoma

Note: Some cytologic clues to salivary duct carcinoma are the presence of high grade malignant features and background necrosis. A diagnosis may be suggested on cytology, and supported by the GATA3 and AR (Androgen receptor)-positive immunoprofile. However, on cytology, the more clinically important information that needs to be included in the report is the presence of malignancy and the high grade appearance of the malignant cells, even if the specific diagnosis may not be possible.