Cytological features of cystadenocarcinoma in cyst fluid of the parotid gland: Diagnostic pitfalls and literature review

Abstract

Cystadenocarcinoma is a rare malignant tumor, with an estimated incidence of 2% of malignant salivary gland tumors. Cytological diagnosis of cystadenocarcinoma is important for differential diagnosis between benign lesions and malignant tumors with cystic growth. We report a case of cystadenocarcinoma causing difficulty in cytological diagnosis. A 23-year-old man presented with an asymptomatic mass in the left parotid gland that had been present for 2 years. The mass was elastic hard, measuring 30 x 35 mm in diameter. Preoperative fine-needle aspiration cytology (FNAC) showed a small number of tumor cell clusters in the cystic fluid. The cluster was arranged in a ball-like structure and was cohesive with overlapping. Tumor cells had a small vacuolated, soap-bubble appearance in the cytoplasm. The papillary-cystic variant of acinic cell carcinoma (ACC-PCV) was suggested from these findings on FNAC. Histologically, the tumor was not encapsulated, but formed large cystic spaces against a background of fibrous connective tissue. The tumor cells in the cystic dilated duct showed papillary structures, which were continuous with the lining cuboidal cells. There was neither a definite double-layered arrangement in cystic ducts and solid islands nor histological findings characteristic of the papillary-cystic or follicular pattern of ACC-PCV. As tumor cells with a small vacuolated, soap-bubble appearance of the cytoplasm are common findings of both cystadenocarcinoma and ACC-PCV, they are of little use for differentiation; however, they are so characteristic that the majority of benign salivary gland lesions with cystic structures can be excluded, if enough attention is paid.

Cystadenocarcinoma simulating hemangiosarcoma of the salivary gland in dog: case report

“…Currently, several papers have used immunohistochemistry in order to characterize hemangiosarcomas (angiosarcomas), and distinguish them from tumors that mimic the formation of vascular spaces by means of particular antibodies. The positivity for cytokeratins was also reported in other studies (Pollett et al, 1997;Kawahara et al, 2009) Diagn. Cytopathol., v.37, p.128-131, 2008. BUYUKMIHCI, N.; RUBIN, L.F.; HARVEY, C.E.…”

“…However, this technique is not extremely effective, as cystadenocarcinomas with PAS-negative neoplastic cells have been reported in humans, as well as observed in this report (Kawahara et al, 2009).…”

Papillary-Cystic Variant of Acinic Cell Carcinoma in the Lacrimal Gland

“…Currently it is classified as one of a number of low-grade salivary duct carcinomas, which include cystadenoma, cystadenocarcinoma, sclerosing polycystic adenosis, oncocytoma, and salivary duct carcinoma in situ [3]. A diagnosis is difficult based on fine needle aspiration cytology alone [4, 5]. The cystic nature of the tumour dilutes the cellularity of the sample that is obtained and the cytoarchitecture is different from acinic cell carcinoma [4].…”

“…The PCV-ACC cells themselves are also different in appearance from acinic cell carcinoma by having a polygonal appearance that can mimic clear-cell carcinoma [4]. The cystic nature can lead to misinterpretation of a mucin background and misdiagnosis as cystadenocarcinoma [5, 6]. The rare nature of the tumour can lead to misdiagnosis too, with samples misinterpreted as being commoner tumours [1, 6].…”

An invasive adenocarcinoma of the accessory parotid gland: a rare example developing from a low-grade cribriform cystadenocarcinoma?

“…Sebaceous cell-like foamy cells with microvacuoles are sometimes seen in cystadenocarcinoma of the salivary gland. Intracytoplasmic vacuoles are found also in PCV-ACC, but uniformly-sized, fine microvacuoles might be considered characteristic of cystadenocarcinomas, including LGCCA, rather than PCV-ACC [19]. Another differential diagnosis is SDC.…”