Inflammatory breast cancer

Inflammatory breast cancer is a rare and aggressive form of breast cancer that presents with rapid-onset redness, swelling, and skin thickening of the breast — symptoms that often mimic infection — rather than as a discrete lump.

IBC accounts for around 1–5% of breast cancers¹ but is one of the most important diagnoses not to miss because it can look like a breast infection. It is faster-growing than typical breast cancer and is treated with a defined sequence: chemotherapy first, then mastectomy with axillary clearance, then radiotherapy, with adjuvant therapy based on receptor status. Outcomes have improved with this multimodal approach but remain less favourable than for typical invasive breast cancer at the same stage.

Orientation Why you might be reading about this

You may have been told that IBC is being considered, or you are reading because you have a red, swollen breast that is not responding as expected to treatment for an infection. The reason this entry exists is that IBC is the diagnosis that must not be missed when a breast looks inflamed but does not settle on antibiotics — and recognising the pattern is the most useful thing this page can do.

Related terms: Invasive ductal carcinoma · Invasive lobular carcinoma · Mastectomy · Core biopsy

Presentation How IBC presents

Inflammatory breast cancer is named for how it looks, not how it grows microscopically. Unlike most breast cancers, which present as a discrete lump, IBC presents with a constellation of skin and breast changes:

• Rapid-onset redness of the breast — sometimes covering more than a third of the breast surface — typically over weeks rather than months.
• Swelling and a feeling of heaviness of the affected breast, often noticeably larger than the other side.
• Skin thickening with a dimpled, pitted appearance — sometimes called peau d’orange (French for “orange peel skin”), reflecting the appearance of the deeply tethered skin pores against thickened tissue.
• Warmth and tenderness of the affected breast.
• No discrete lump in many cases — examination may feel diffuse thickening rather than a defined mass.
• Inverted or flattened nipple in some cases.
• Enlarged lymph nodes under the arm.

The pattern develops quickly — typically over 3 to 6 weeks¹ — distinguishing it from the slow growth of most breast cancers. The presentation can be mistaken for mastitis or a breast abscess, particularly outside of the breastfeeding context.

Why it matters Why the “infection that doesn’t settle” pattern matters

Most cases of red, swollen breast in clinical practice are infection (mastitis or abscess). The standard first step is antibiotics³, with the expectation of improvement within 48–72 hours.

A red, swollen breast that does not settle within 48–72 hours of appropriate antibiotics is a red flag for IBC¹. At that point, the pathway changes: prompt imaging (mammogram, ultrasound, often MRI) and biopsy of the skin and underlying breast tissue are arranged, even when infection seems the more likely diagnosis. This caution is built into UK breast practice precisely because IBC can look like infection.

For more on the differential, see mastitis and breast abscess.

Diagnosis Diagnosis

The diagnostic pathway for suspected IBC includes:

• Clinical examination — documenting the extent of the skin changes and breast asymmetry.
• Mammogram and ultrasound — looking for an underlying mass, skin thickening, and enlarged lymph nodes. Sometimes the imaging is more diffuse than for typical breast cancer, with no discrete mass.
• Breast MRI — often added because it shows the extent of disease in the breast and skin more clearly.
• Core biopsy — of any underlying mass or thickened area, plus a skin punch biopsy to look for cancer cells in the dermal lymphatic vessels (the microscopic feature that distinguishes IBC).
• Staging investigations — usually CT chest/abdomen/pelvis and a bone scan, because IBC has a higher chance of metastatic spread at presentation than typical breast cancer.

The diagnosis of IBC is based on the clinical pattern plus biopsy confirmation of cancer. Cancer cells in dermal lymphatic vessels are characteristic but not always seen on biopsy; the clinical picture remains the most important factor.

Treatment Treatment

IBC is treated as stage III breast cancer at minimum and follows a defined multimodal sequence:

1. Neoadjuvant chemotherapy — chemotherapy before surgery, given over several months. For HER2-positive IBC, targeted antibody therapy (trastuzumab plus pertuzumab) is added to chemotherapy.
2. Mastectomy with axillary clearance — IBC is not usually a candidate for breast-conserving surgery because of the diffuse skin and breast involvement. Sentinel lymph node biopsy is generally not used; full axillary clearance is the standard.
3. Radiotherapy — to the chest wall and regional lymph nodes after surgery.
4. Adjuvant systemic therapy — hormone therapy for ER-positive IBC, continued targeted therapy for HER2-positive IBC, and (in selected cases) further chemotherapy or newer agents such as PARP inhibitors for BRCA-positive triple-negative IBC.

Reconstruction is usually delayed — performed months or years after the radiotherapy course is complete, rather than at the time of mastectomy — because immediate reconstruction is more vulnerable to radiotherapy effects in the IBC setting.

The whole treatment pathway typically runs over 9–12 months from diagnosis¹.

Outlook Outlook

IBC is more aggressive than typical breast cancer and outcomes are less favourable when matched for stage. With modern multimodal treatment, however, outcomes have improved meaningfully — particularly for HER2-positive IBC, which has benefited from targeted therapy. Specific prognostic figures depend on the receptor status, response to neoadjuvant therapy, and the presence or absence of distant spread at diagnosis.

At consultation What to discuss with your surgeon

If IBC is being considered:

• The diagnostic pathway — imaging, biopsy of breast tissue and skin, staging investigations.
• The treatment sequence — chemotherapy first, then surgery, then radiotherapy.
• Why mastectomy rather than lumpectomy — IBC is not generally a candidate for breast-conserving surgery.
• Reconstruction planning — delayed rather than immediate, because of radiotherapy.
• Genetic testing — IBC sometimes prompts genetic testing, particularly if triple-negative or in younger patients.

Resources Further reading

• NHS — Breast cancer in women — patient overview.
• Breast Cancer Now — Inflammatory breast cancer — patient-focused guide.
• Macmillan Cancer Support — Inflammatory breast cancer — patient guide.
• Breastory: Mastitis and breast abscess · Skin and nipple changes assessment · Glossary: invasive ductal carcinoma