Adenoid Cystic CA : Grading
Grading of adenoid cystic carcinoma (ACC) is based on tumor architecture. and it has a tremendous impact on prognosis. Grade 1 – shows tubular or mixed tubular and cribriform pattern with no solid areas. The tumor is cytologically bland with no or scant mitoses. Ki67 labeling index is low. Recurrence rate is 59% and 15-yr survival rate is 39%. Grade 2 – shows pure cribriform or cribriform with solid areas (solid foci should be < 30% of the tumor). Cytologic atypia is greater than Grade 1. Recurrence rate is 89% and 15-yr survival rate is 26%. Grade 3 – tumor with > 30% solid component irrespective of other patterns. There is greater cytologic atypia, increased mitotic activity and areas of necrosis. Ki67 labeling index is high. Recurrence rate is 100% and 15-yr survival rate is 5%. This low magnification shows tubular architecture and anastomosing trabeculae lined by a single layer of ductal epithelial cells surrounded by one or more layers of basaloid cells. The tubules are separated by hyaline stroma creating a delicate lace-like pattern. The tumor location was one of the paranasal sinuses.