Fig. 2.

Distinguishing high-grade salivary tumors with comedo-type necrosis from salivary duct carcinoma (SDC). a Adenoid cystic carcinoma (AdCC) with high-grade transformation (HGT). Basophilic appearance, cribriform growth pattern, and pseudo-lumena filled with basement membrane-like material raise the possibility of an AdCC. 14 months after the initial diagnosis of SDC, the patient developed pulmonary metastases with unequivocal, classic AdCC morphology. H&E, 100x. b Acinic cell carcinoma with HGT. A minority of cells surrounding foci of necrosis have numerous cytoplasmic zymogen granules, best appreciated on PASD, 400x. c High grade myoepithelial carcinoma. Solid sheets of neoplastic cells do not form glands and are accompanied by droplets of hyalinized material. Nuclear palisading was absent. H&E, 200x. d Epithelial-myoepithelial carcinoma with HGT: an area with comedo-type necrosis is accompanied by a better-differentiated component with dual cell population: smooth muscle actin immunohistochemistry highlights the outer layer of myoepithelial cells (right upper corner inset, 200x). H&E, 100x.

Modified from [4] with permission