Definitive Diagnosis of Inflammatory Breast Cancer
The definitive diagnosis of inflammatory breast cancer is provided by finding tumour emboli in dermal lymphatics (option B), which is pathognomonic for IBC, although not required for diagnosis.
Diagnostic Criteria for Inflammatory Breast Cancer
The diagnosis of inflammatory breast cancer (IBC) is primarily clinical with essential pathological confirmation of invasive carcinoma. The following criteria are required:
- Rapid onset of breast erythema, edema and/or peau d'orange, and/or warm breast, with or without an underlying palpable mass 1
- Duration of history of no more than 6 months 1
- Erythema occupying at least one-third of the breast 1
- Pathological confirmation of invasive carcinoma from a core biopsy 1
Pathological Features and Dermal Lymphatic Invasion
While the diagnosis is primarily clinical, pathological features play a crucial role:
- Dermal lymphovascular tumor emboli are considered the histological hallmark of IBC 1
- When present in skin punch biopsy, dermal lymphatic invasion (DLI) is pathognomonic for IBC 1
- DLI presents as dilated dermal lymphovascular spaces filled with tumor emboli that are often retracted away from the surrounding endothelial lining 1
- Despite being pathognomonic, DLI is identified in <75% of patients with IBC, making it not an absolute requirement for diagnosis 1
Role of Imaging in Diagnosis
- Mammography and other radiological investigations are recommended as part of staging work-up, not for diagnosis 1
- Current evidence is insufficient to define any radiological signs specific for IBC 1
- Unique mammographic appearance (option A) is not considered diagnostic for IBC 1
Inflammatory Cell Infiltration
- Finding extensive inflammatory cell infiltration of the tumor (option C) is not diagnostic of IBC 1
- The term "inflammatory" in IBC refers to the clinical appearance of the breast (erythema, edema) rather than the presence of inflammatory cells in the tumor 2, 3
Recommended Diagnostic Approach
- Core biopsy to confirm invasive carcinoma 1
- Strongly recommended that every patient who meets the clinical diagnostic criteria undergo at least two skin punch biopsies 1
- The best area to sample is the most prominent area of skin discoloration 1
- All IBC tumors should be tested for hormone receptors and HER2 status 1
Common Pitfalls in Diagnosis
- IBC is often misdiagnosed as mastitis or generalized dermatitis due to its rarity 3
- Relying solely on imaging findings without clinical correlation may lead to missed diagnoses 1
- Failure to perform skin punch biopsies may miss the opportunity to identify pathognomonic dermal lymphatic invasion 1
- Waiting for response to antibiotics may delay diagnosis, as patients may have a history of being diagnosed with mastitis not responding to at least 1 week of antibiotics 1
In conclusion, while the clinical presentation forms the foundation of IBC diagnosis with pathological confirmation of invasive carcinoma, the finding of tumor emboli in dermal lymphatics provides the most definitive and pathognomonic evidence of inflammatory breast cancer, though it is not required for diagnosis.