Histologic grading of adenoid cystic carcinoma of the salivary glands

TLDR

Prognosis of adenoid cystic carcinoma depends on primary site, margin status, and involved anatomical structures. The study examined whether tumor morphology correlates with prognosis in 79 salivary gland adenoid cystic carcinoma patients. Tumors were classified into three histologic grades based on the proportion of solid, tubular, and cribriform patterns. Grade III tumors had the worst prognosis with only 5% 15‑year survival, frequent recurrence, and early mortality, while Grade I tumors had the best outcome with 39% 15‑year survival, smaller size, and amenability to complete excision, and Grade II tumors fell intermediate.

Abstract

Seventy-nine patients with adenoid cystic carcinoma arising in salivary glands were studied to determine whether a correlation existed between the morphologic features of the tumor and the prognosis. Three histologic grades were established: Grade I, tumors with tubular and cribriform areas but without solid components; Grade II, cribriform tumors that were either pure or mixed with less than 30% of solid areas; and Grade III, tumors with a predominantly solid pattern. Cumulative survival rates at 15 years were 39%, 26%, and 5%, for Grades I, II, and III, respectively. Grade III tumors were larger, recurred frequently, and killed the patients within 4 years. Grade I lesions were smaller, were amenable to complete surgical excision, and had a protracted clinical course. Grade II tumors lay between the other two forms both clinically and pathologically. Other important prognostic features of the adenoid cystic carcinoma were its primary site, its presence or absence at surgical margins, and the anatomic structures it involved.