Necrotising cellulitis of the breast associated with a fungating mucinous adenocarcinoma.

Breast necrotising soft tissue infections (NSTIs) are rare surgical emergencies with limited cases described in the literature. Here, we discuss a unique case of a woman in her 70s who presented with newly diagnosed diabetes and a neglected right breast cancer associated with breast erythema, skin necrosis, crepitus on examination and breast soft tissue gas seen on CT requiring emergent total mastectomy with partial pectoralis muscle excision. Pathology revealed a 15 cm invasive mucinous adenocarcinoma and necrotising polymicrobial cellulitis with a large abscess cavity. She recovered from her surgery with strict glycaemic control and a 10-day course of antibiotics. Multidisciplinary tumour board recommended adjuvant anastrozole, abemaciclib and postmastectomy radiation to complete her oncological treatment. Although exceedingly rare, it is important that clinicians be aware of, promptly recognise and properly treat NSTIs of the breast, as correct care can be life-saving from both infection and malignancy.