Anatomic Pathology / Cystic Neutrophilic Granulomatous Mastitis

Although granulomatous lobular mastitis is associated with gram-positive bacilli such as Corynebacterium, this association is not well known. We report 3 cases of mastitis caused by gram-positive bacilli. All 3 abscesses were suppurative with distinct enlarged cystic spaces in which rare gram-positive bacilli were identified. Two cases were also granulomatous. Cultures in all 3 cases were negative. All 3 patients recovered after biopsy and tetracyclinebased therapy. Infection in the breast by gram-positive bacilli is associated with a distinct histologic pattern, including cystic spaces in the setting of neutrophilic/ granulomatous inflammation that can be recognized and should prompt careful search for the organism within enlarged vacuoles. Breast abscesses are not uncommon and are associated with a variety of infectious organisms, particularly bacteria.1-8 In most cases, these bacterial infections are associated with nonspecific acute and chronic inflammation and reactive changes. While many bacteria are easily cultured from tissue specimens, some organisms can be harder to grow, and a small percentage of cultures from breast abscesses remains negative.3,6-7 In 2003, Taylor et al9 reported a landmark series of 34 breast abscesses with distinct histologic features that were associated with Corynebacterium infection. Most cases were granulomatous, but all cases had a suppurative component with distinct vacuoles that were thought to represent dissolved lipid. Organisms were identified by Gram stain in 16 cases, but in every case, the organisms were rare, often missed on initial review of the Gram stain, and found only within the vacuoles. Although corynebacteria were identified by culture in every case, it was noted that culture of Corynebacterium can be difficult and may not be possible without special culture techniques, including the use of 1% polysorbate (Tween) 80. Despite this excellent study,9 appreciation of the distinct features of Corynebacterium infection in breast abscesses is not well recognized. We were unable to find a citation of this report in any standard breast pathology or general pathology textbook. To help bring this recognizable histologic pattern to the attention of the general pathology community, we report 3 additional cases of breast abscesses with the same suppurative inflammation with vacuoles and granulomas associated with gram-positive bacilli. Upon completion of this activity you will be able to: • recognize that cystic neutrophilic/granulomatous inflammation in breast abscesses is associated with infection with gram-positive rods. • recognize that cultures are often negative in this setting, and that gram-positive rods are often rare and found only in the cystic spaces. • describe possible types of infections that can be seen in breast abscesses. The ASCP is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASCP designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 Credit TM per article. Physicians should claim only the credit commensurate with the extent of their participation in the activity. This activity qualifies as an American Board of Pathology Maintenance of Certification Part II Self-Assessment Module. The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose. Questions appear on p 479. Exam is located at www.ascp.org/ajcpcme. Downloaded from https://academic.oup.com/ajcp/article-abstract/136/3/424/1760725/Cystic-Neutrophilic-Granulomatous-MastitisAn by guest on 02 October 2017 Am J Clin Pathol 2011;136:424-427 425 425 DOI: 10.1309/AJCP1W9JBRYOQSNZ 425 © American Society for Clinical Pathology Anatomic Pathology / Original Article