Invasion patterns of metastatic high-grade serous carcinoma of ovary or fallopian tube associated with BRCA deficiency

High-grade serous carcinomas of the uterine adnexa with BRCA1 deficiency (high-grade serous carcinomas-BRCA) have recently been described to demonstrate characteristic histopathological features. We hypothesize that metastatic high-grade serous carcinomas-BRCA cases exhibit characteristic morphological features as well. We studied 102 high-grade serous carcinomas with known BRCA1 and BRCA2 genotype from the archives of the Department of Pathology at Memorial Sloan-Kettering Cancer Center. The primary site morphological characteristics of these cases were reported previously; we now focus solely on tumor morphology in sites other than the uterine adnexa (ie, metastatic sites). The study group consisted of the following case types: 13 BRCA1 germline mutations; 5 BRCA1 somatic mutations; 10 BRCA1 promoter methylation; 4 BRCA2 germline mutations; 1 BRCA2 somatic mutation; 11 lacking BRCA1 or BRCA2 abnormality; 58 cases lacking BRCA1 or BRCA2 germline mutation. Two observers independently scored invasion patterns and microscopic tumor architecture while blinded to genotype. Concordance between observers and correlations between metastatic patterns and the following indices were studied: genotype, primary site tumor characteristics, and BRCA1 immunohistochemistry. Concordance between observers was excellent (κ values >0.9). All cases with BRCA1 or 2 abnormalities showed either pushing pattern metastases (76%) or infiltrative metastases composed only of micropapillae (24%). In contrast, all cases lacking BRCA1 or 2 abnormalities showed infiltrative metastases that contained combinations of papillary, glandular, and, rarely, cribriform and micropapillary architecture (P