Abstract

Background: Idiopathic granulomatous mastitis (IGM) is a rare, benign inflammatory disease of the breast and is known to have a strong association with pregnancy and lactation. Diagnosing IGM can be delayed as it is often mistaken for infection leading to a period of ineffective antibiotic therapy which defers the appropriate treatment. A differential diagnosis of IGM should be considered in all inflammatory breast masses that have an atypical presentation (large solid component, sinus formation, fistulation, multiple areas) or after a short period of failed empirical antibiotic therapy (1–2 weeks). Core biopsy should be taken at an early stage to rule out neoplasm and confirm the diagnosis of IGM. IGM is characterised histologically by non-caseating lobulocentric granulomatous inflammation. The presence of the Corynebacterium kroppenstedtii bacterium is widely associated with the onset of IGM. There is a lack of consensus for optimal treatment for IGM which can make this condition challenging for clinicians to manage. The management of IGM should follow a multi-disciplinary approach. Case Description: We report a case of a 31-year-old woman with IGM refractory to steroid treatment whose disease was successfully treated and kept in remission during a subsequent pregnancy using a new regimen of azathioprine and allopurinol. This case highlights the challenges in diagnosing and treating IGM; a condition commonly associated with prolonged suboptimal management with extended antibiotic and glucocorticoid therapy as well as limited treatment options for women who are pregnant and/or breastfeeding. Conclusions: This case has guided the development of a new complex breast abscess and IGM treatment algorithm to guide management in all women including those in the pregnancy and post-partum period. It involves a multidisciplinary team approach and is a useful tool to clinicians in ensuring prompt diagnosis, targeted therapy and the avoidance of unnecessary operative management.