Low-grade cribriform cystadenocarcinoma of salivary glands: report of two cases and review of the literature

Abstract

Low-grade cribriform cystadenocarcinoma (LGCCC) is a recently described rare tumor of salivary gland which exhibits clinically indolent behavior. This tumor predominantly consists of intraductal components and frequently exhibits papillary-cystic or cribriform proliferation pattern. Considering the histological features of LGCCC, it should be distinguished with papillocystic variant of acinic cell carcinoma, conventional salivary duct carcinoma, cystadenocarcinoma, polymorphous low-grade adenocarcinoma, carcinoma ex pleomorphic adenoma and mammary analogue secretory carcinoma. Herein, we presented two cases of LGCCC. One arose in the left parotid region in a 48-year-old male, and the other one arose in the right parotid gland in a 59-year-old female. For both cases, immunohistochemically, the luminal tumor cells showed diffuse expression of CK and S100; p63 and smooth muscle actin displayed a continuous rim of myoepithelial cells around all tumor islets; no myoepithelial cells were admixed with the luminal cells. Both patients were alive with no tumor recurrence or metastasis at follow-up.

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Figure 1

Histological features and immunohistochemical staining of both cases. A-B: Case 1, the tumor was demarcated from the surrounding slightly lipomatous parotid glands with a relative boundary. C-D: Case 1, within the tumor, solid and micropapillary pattern were observed. E-F: Case 2, the tumor was demarcated from the surrounding parotid glands with a clear boundary. G: Case 2, the tumor cells were uniform without significant cytologic and nuclear atypia. They displayed round to oval nuclei with fine chromatin and pale to amphophilic cytoplasm. H: Case 2, Apocrine differentiation of tumor cells was observed focally. I: The luminal tumor cells showed diffusive expression of S100 (Case 1 and 2). J: Immunostaining for p63 displayed a continuous rim of myoepithelial cells around all tumor islets (Case 1 and 2).