Abstract
It has been difficult cytologically to distinguish salivary duct carcinoma (SDC) from highโgrade carcinoma. We investigated the microscopic cytological findings, morphometric image analyses, and immunohistochemical features of SDC, focusing on how we achieved an accurate differential diagnosis distinguishing SDC from salivary gland carcinomas with squamous differentiation. Immunohistochemical staining was performed for androgen receptor (AR), gross cystic disease fluid proteinโ15 (GCDFP15), mammaglobin, human gastric mucin, MUC1, MUC2, p63, and cytokeratin high molecular weight. Of the 13 cases of SDC, 9 cases showed typical cytological findings of sheet clusters with polygonal granular cytoplasm with fine chromatin. The other 4 cases showed unusual cytological findings of a pseudoโpapillary cluster or scattered cells only, and the tumor cells showed coarse chromatin. Morphometric image analysis showed that the nucleus area was statistically different between SDC and salivary gland carcinomas with squamous differentiation. ARโpositive expression (P = 0.008), GCDFP15โpositive expression (P = 0.005) and p63โnegative expression (P = 0.001) were effective as SDCโspecific markers in immunohistochemistry. An accurate cytological diagnosis of SDC can be determined by immunostaining with AR, GCDFP15, and p63, based on the nuclear findings. Diagn. Cytopathol. 2008;36:485โ493. ยฉ 2008 WileyโLiss, Inc.