Carcinoma en cuirasse is a rare form of cutaneous metastasis commonly associated with breast cancer. While metastasis to skin is common in breast cancer, the incidence of carcinoma en cuirasse is estimated at between 0.7 to 9%.
We report the case of a 71-year-old female patient with metastatic oestrogen receptor positive, HER2 negative lobular breast cancer to the peritoneum, bones, pleura and lymph nodes. She also had a contralateral left sided oestrogen receptor positive, HER2 positive inflammatory lobular breast cancer initially treated with the combination of pertuzumab, trastuzumab and docetaxel. After cessation of weekly docetaxel after four cycles, the patient developed plaque-like, confluent lesions encasing the entire abdomen. This was associated with intense pruritus, disseminated erythema, indurated and thickened skin as well as oedema. Core biopsy of the skin was performed which showed infiltration of the dermal lymphatics with malignant epithelial cells. The cells tested positive for the oestrogen receptor and negative for the HER2 receptor. The patient was reviewed in the dermatology clinic for management of the pruritus and recommenced on docetaxel by the medical oncologist. After two cycles of weekly docetaxel the skin lesions significantly improved, the skin softened and erythema reduced.
This case demonstrates the importance of biopsies in metastatic breast cancer patients to assess receptor status and guide treatment strategies. Carcinoma en cuirasse is a rare presentation of breast cancer however easily manageable with the combination of effective anti-cancer therapies and adjunctive medications to manage the associated dermatological manifestations.