Granulomatous mastitis (GM) of the breast has long posed a clinical dilemma in terms of diagnosis and management. GM can range from acute to chronic inflammations, which will have treatment implications. Inflammation of the breast may clinically mimic breast carcinomas and pyogenic abscesses. Thus, in the absence of known etiology, such as trauma or breastfeeding, GM may be difficult to diagnose. Currently, the incidence of GM is 2.4 per 100,000 women and 0.37% of the total population in the US. The rarity of GM contributes to it being a poorly understood disease. It has no definite clinical features and is often confused with a neoplasm or infection clinically and radiologically.

The study aimed to describe the clinical characteristics of GM seen in the Breast Care Clinic in the Philippine General Hospital (PGH) from January 2015 to June 2019. This study would initially provide institutional data on GM that is relevant in the Philippines.

This is a retrospective observational study of patients with GM seen in the Philippine General Hospital, a national tertiary referral hospital, from January 2015 to June 2019.

A total of 43 patients with pathological findings of GM from January 1, 2015 to June 15, 2019 were recorded. Among these 43 patients, 98% were female. The median age was 38.9 ± 11.3 years old. In 60.5% (26 out of 43) of patients, the initial impression was breast malignancy. The most common clinical presentation in 69.8% (30 out of 43) of the subjects was a breast mass. In more than 50% of the patients, breast ultrasonography was the initial imaging performed. The histopathologic profile of the patients showed inflammation, of which, the greatest were that of chronic granulomatous inflammation (46.5%, n-20). Treatment options performed were tended more medical (53.5%, n-23) than surgical (16.3%, n-7).Among those who received medical treatment, the therapeutics given were antitubercular medications (34.9%, n-15) and antibiotics (16.3%, n-7), while the others had a combination of antitubercular and antibiotic regimen medications (2.3%, n-1); unknown treatment (25.6%, n-11) and none (11.6%, n-5). For patient outcomes, no mortalities were recorded during the study period. However, most patients had inconsistent followups. Approximately 7%-23% of the patients who had followed up within the six months showed improvement or resolution of symptoms.

This study assessed the clinical profiles of patients with GM in a national tertiary referral hospital. Internationally, there is still no consensus on the algorithm and management of GM patients. However, the authors recommend a close follow-up every two weeks to re-evaluate patient response to the medical regimen being administered. The authors recommend a prospective study with a longer follow-up period to gain a deeper understanding of GM in Filipinos.