Diagnosis: Basal cell adenocarcinoma
• Salivary gland malignancies may share considerable morphologic overlap. Recognition of features that characterize specific lesions is consequently important.
• Basal cell adenocarcinoma sometimes shows small collections of matrix material within nests of tumor cells. This finding may help distinguish basal cell adenocarcinoma from mimics, such as adenoid cystic carcinoma.
• Within cribriform areas of adenoid cystic carcinoma, pseudocysts contain either mucoid basophilic material (glycosaminoglycans) or hyaline eosinophilic material (reduplicated basal lamina). These pseudocysts are generally distinguishable from the small collections of matrix material that sometimes appear in basal cell adenocarcinoma.
• Basal cell adenocarcinoma characteristically shows prominent palisading within nests of lesional cells. This finding may help distinguish basal cell adenocarcinoma from mimics, such as epithelial-myoepithelial carcinoma.
• Basal cell adenocarcinoma commonly shows partial circumscription/encapsulation, unlike adenoid cystic carcinoma, which characteristically demonstrates extensively invasive growth.
