Cytomorphological findings and histological correlation of papillary cystadenocarcinoma of the parotid: Not always a low-grade tumor.

Papillary cystadenocarcinoma (PCAC) is a rare salivary gland tumor characterized by a predominantly cystic growth that often exhibits intraluminal papillary growth without specific histologic features of other cystic salivary gland tumors. The preoperative cytological diagnosis can pose a diagnostic challenge as it has to be differentiated from other cystic papillary tumors such as mucoepidermoid carcinoma, papillary cystic variant of acinic cell carcinoma, and low-grade cribriform CAC. It is considered to be a low-grade malignant salivary gland tumor with an indolent biological behavior. We report a case of PCAC of the parotid in a 55-year-old male diagnosed on fine needle aspiration cytology. Although it showed mild atypia cytologically, on excision tumor showed vascular and perineural invasion with regional node metastasis indicating a wider morphologic spectrum than what is described. This prompted us to write a case report describing the cytological and histological features of this rare tumor and also discuss the diagnostic challenges.