A biological systems approach to classification of acute and end-stage breast inflammation in the lactating breast

Breast inflammation is a spectrum condition in lactation

The interaction between networks of inflammatory signals within the lactating mammary gland immune system, triggered by high intraluminal pressures, determines the severity of breast inflammation, its duration, and resolution.

The common diagnoses used on the spectrum of breast inflammation are poorly defined and have overlapping presentations. For this reason, NDC proposes a complex systems approach to the spectrum of breast inflammation presentation, which results in a classification system using two main categories

1. Acute breast inflamation

2. Endstage breast inflammation.

Acute lactation-related breast inflammation

The first, benign lactation-related breast inflammation, is described clinically by relevant presenting signs and symptoms, selected from signs and symptoms on the spectrum of breast inflammation detailed in the table below.

Engorgement, a diagnosis with clearer and agreed definition, is conceptualised as a bilateral and generalised presentation of breast inflammation. From a complexity science perspective, breast inflammation emerges out of multiple interacting systems, and is located along a spectrum of severity, spread, and systemic involvement.

When acute breast inflammation becomes more severe, whether localised or generalised, systemic responses of fever, myalgia, and rigor are triggered.

End-stage lactation-related breast inflammation

The second category is end-stage (non-malignant) inflammation of the lactating breast, with sub-categories of active or inactive. Three well-defined diagnoses fall within the category of active, end-stage (non-malignant) inflammation of the lactating breast: abscess, fistula and septicaemia. Though non-malignant, these conditions are also not benign.

An abscess is described by the relevant presenting signs and symptoms of lactation-related breast inflammation selected from the table below.

The diagnosis of galactocoele, also well-defined, sits within the category of inactive, end-stage (non-malignant or benign) inflammation of the lactating breast. A galactocoele is also described by the relevant presentation of signs and symptoms detailed below.

Clinical signs and symptoms used to classify acute and end-stage breast inflammation

This table is designed to be placed in medical records so that the relevant sign or symptom highlighted.

Location of inflammation	Dimensions (millimetres)	Erythema	Pain	Systemtic signs + symptoms
Generalised - bilateral		None	None	Feels well
Generalised - unilateral R or L		Mild	Mild when touched only	Fever
Localised WITHOUT lump		Moderate	Mild constant	Myalgia
Localised WITH lump		Severe	Moderate when touched only	Rigor
			Moderate constant
			Severe

Alipour et al 2025

This multicenter survey-based Iranian study of 1490 women demonstrates the link between increased incidence of milk stasis during breastfeeding and subsequent idiopathic granulomatous mastitis (IGM). This finding places IGM on the NDC spectrum of lactation-related breast inflammation, as another kind of end-stage breast inflammation.

Selected references

Alipour S, Tabatabaian M, Aziminezhadan P. From hypothesis to robust evidence in a nationwide multicenter case-control study on 1490 women: milk stasis and idiopathic granulomatous mastitis. Scientific Reports. 2025;15:37576. https://doi.org/37510.31038/s41598-37025-10784-37577

Ingman WV, Glynn DJ, Hutchinson MR. Inflammatory mediators in mastitis and lactation insufficiency. Journal of Mammary Gland Biology and Neoplasia. 2014;19:161-167.

Douglas PS. Re-thinking benign inflammation of the lactating breast: classification, prevention, and management. Women's Health. 2022;18:17455057221091349.

Guillen-Morales DdJ, Cruz-Cortes I, Sosa-Velazco TA, Aquino-Dominguez AS. The mother-infant symbiosis: a novel perspective on the newborn's role in protecting maternal breast health. Hygiene. 2025;5(46):https://doi.org/10.3390/hygiene5040046.