Primary ductal adenocarcinoma of the lacrimal gland, associated with abundant intracytoplasmic lumens containing some eosinophilic hyaline globules: cytological, histological and ultrastructural findings.

A primary ductal adenocarcinoma (PDA) of the lacrimal gland is a rare distinct subtype of an epithelial tumor arising in the lacrimal gland. PDA is the counterpart of salivary duct carcinoma (SDC) resembling an invasive ductal carcinoma (IDC) of the breast. In our case, PDA revealed histopathological and immunohistochemical results corresponding to SDC. Interestingly, the tumor cells showed intracytoplasmic vacuoles containing dense eosinophilic hyaline globules at light microscopy. Ultrastructurally, the tumor cells exhibited microvilli-lined intracytoplasmic lumen containing homogenous electron-dense secretory products. A previous study demonstrated that numerous intracytoplasmic lumens of tumor cells are favored breast malignant tumor, similar to the histopathology of PDA, rather than benign lesion. This characteristic finding may be meaningful to diagnose high grade epithelial tumors including PDA.