Lactational phlegmon: A distinct clinical entity affecting breastfeeding women within the mastitis-abscess spectrum

We aimed to describe the presentation and treatment of lactational phlegmon, a unique complication of mastitis in breastfeeding women that may require surgical management. We retrospectively analyzed medical charts of breastfeeding women treated by a single breast surgeon for lactational phlegmon or the related conditions of abscess or uncomplicated mastitis (UM) from July 2016 to October 2018. Demographic variables and treatment details were analyzed using ANOVA and Pearson's Chi-square test. Ten women with lactational phlegmon (19.2%), 15 women with abscess (28.8%), and 27 women with UM (51.9%) were identified. Phlegmon presented as a tender, erythematous, and nonfluctuant mass in a ductal distribution. Ultrasonography demonstrated an ill-defined, complex fluid collection. Epidemiologically, women with phlegmon were similar to patients with abscess and UM. Women with phlegmon reported more intense deep breast massage than patients in the other two groups, but significantly lower rates of breast pump use than women with abscess (30.0% vs 80.0%, P < .05). Relative to women with UM, patients with complicated mastitis (CM, defined as phlegmon or abscess) reported greater utilization of nipple shields (36.0% vs 11.1%, P < .05). Treatment of phlegmon entailed effective milk removal, antibiotics (range 10-30 days), and close follow-up until both clinical and radiographic resolution (range 8 days to >3 months), with biopsy of persistent masses. Antibiotic duration was significantly longer for patients with phlegmon compared to those with UM (mean 15.0 days vs 9.7 days, P < .05). Two phlegmons coalesced into abscesses within 1 week of diagnosis. Lactational phlegmon is a complication of mastitis in breastfeeding women that is distinct from abscess and UM. Optimal treatment consists of an extended course of antibiotics and close follow-up to monitor for coalescence into a drainable fluid collection and/or persistence of mass requiring biopsy.