Further Characterization of Clinicopathologic Features of Cystic Neutrophilic Granulomatous Mastitis A Case-Control Study in a Single Large Health System

Objectives Clinical and demographic features of cystic neutrophilic granulomatous mastitis (CNGM) have not been fully explored due to the rarity of the disease. Herein we studied clinicopathologic characteristics of CNGM in a sizable hospital-based cohort. Methods A case-control study was performed to compare clinicopathologic characteristics between patients with CNGM and granulomatous mastitis other than CNGM and between CNGM with and without Corynebacterium identification. Results Cases of CNGM (n = 31) and non-CNGM (n = 30) were included. Compared with the non-CNGM group, patients with CNGM were statistically significantly younger (median age: 38 vs 43 years), were less likely to be smokers (9% vs 40%), were more likely to have a painful lesion (97% vs 77%) or a larger mass-like lesion (median size: 4.6 vs 1.9 cm), and tended to have a higher Breast Imaging Reporting and Data System score in radiologic studies (score >= 4: 81% vs 53%), positive Corynebacterium identification results (36% vs 0%), and a longer resolving time (12 vs 6 months; all P values for above comparisons <.05). Among CNGM cases, patients with and without Corynebacterium identification shared a similar clinicopathologic profile. Conclusions Our study further demonstrated that CNGM is a unique infectious disease with distinct clinicopathologic features.