43. Low grade cribriform cystadenocarcinoma: the cytology and histology of a rare salivary gland tumour

Abstract

Low grade cribriform cystadenocarcinoma (LGCCC) is a rare low grade malignant neoplasm which occurs almost exclusively in the parotid gland. The lesion is also known as low grade intraductal carcinoma of the salivary gland, coined by Delgado et al. in 1996, due to its resemblance to atypical ductal hyperplasia or low grade ductal carcinoma in situ of the breast. The majority of patients are elderly and have a female predominance of 2:1. While there have been several case series and case reports in the literature about its histological and immunohistochemical features, only two studies in the English language literature have given any cytolomorpho-logical description. We present a case of a 62-year-old female with a right parotid mass. A fine needle aspiration showed a hypercelllular smear, with sheet-like and branching architecture, composed of fairly uniform cells with atypical features, in a mucoid/myxoid background. A diagnosis suggestive of a pleomorphic adenoma was given. Five months later, an excision of a 1.5 cm, solid-cystic mass was performed. Histological examination showed an intraductal proliferation of tumour cells akin to a breast low grade ductal carcinoma in situ with papillary and cribriform pattern. A focal area of microinvasion was present. Immunohistochemically, the luminal cells showed strong and diffuse positive cytokeratin and S-100 staining. The myoepithelial marker, calponin, highlighted the basal cells. Hence, a diagnosis of low grade cribriform cystadenocarcinoma was favoured. The characteristic features of this lesion are discussed, with focus given to the cytological findings and the diagnostic difficulties in fine needle aspirates, particularly due to lack in the current literature of definitive diagnostic criteria.