Inflammatory breast carcinoma (IBC) is a distinct clinical entity characterised by peau d'orange appearance and is classified as at least T4d (Stage IIIB) by TNM even without a palpable mass. Its pathological hallmark is:

• A Oestrogen receptor negativity in over 95% of cases
• B HER2 overexpression in all cases
• C Dermal lymphatic invasion by tumour emboli on skin biopsy ✓
• D Microsatellite instability as the universal molecular driver

Explanation

Inflammatory breast carcinoma is defined clinically by rapid onset erythema, warmth, oedema, and peau d'orange of the breast skin. The pathological hallmark is tumour emboli within the dermal lymphatics of the skin biopsy, which causes lymphatic obstruction producing the classic skin changes. IBC is not defined by receptor status or HER2, although HER2 overexpression and ER negativity are more common than in non-IBC. The diagnosis requires histological evidence of dermal lymphatic tumour emboli on skin punch biopsy.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.