Intraductal carcinoma of salivary gland (so-called low-grade cribriform cystadenocarcinoma) arising in an intraparotid lymph node.

Since the first description of an entirely intraductal epithelial proliferation of salivary gland by Chen in 1983 as an "intraductal carcinoma", there have been several dozen reported cases with the same and various additional names including "low-grade salivary duct carcinoma", "low-grade cribriform cystadenocarcinoma" and "carcinoma in situ" of salivary gland. These refer to a combination of nests and cysts of varying size formed by a cellular proliferation resembling atypical ductal hyperplasia or ductal carcinoma in situ of the breast. The lesions are generally entirely intraductal with low, intermediate or high-grade dysplasia. Occasional benign tumors of salivary gland, particularly Warthin tumor and rare salivary carcinomas may arise within an intraparotid lymph node. In addition, intraparotid lymph nodes are a routine location for metastatic disease. A case of a 59-year-old female with a parotid mass is described, which grossly had the appearance of a Warthin tumor. Microscopically, it was an entirely intranodal proliferation of cells with diffuse AE1/AE3 and S100 positivity. The nests and cysts were completely surrounded by a rim of non-neoplastic myoepithelial cells, which were positive for CK14, p63, SMA, MSA and calponin. The tumor cells were negative for these markers. The cells were only focally positive for AR and BRST-2. They showed negligible MIB-1 staining. This report describes, for the first time, an entirely intranodal location for a low-grade intraductal carcinoma (so-called low-grade cribriform cystadenocarcinoma).