Ecchymotic Purpura of the Breast Revealing a Locally Advanced Breast Cancer: An Exceptional Presentation of a Carcinomatous Mastitis.

A 79-year-old woman was treated at our department for a neoplasm of the left breast. It was discovered following the spontaneous appearance of a localized ecchymotic lesion of the breast. The only clinical sign was this purpura, with no notion of trauma. The lesion was homogeneous, oval, and measuring 4 × 5 cm, and it was stable for 2 months. The patient had no history of thrombocytopenia and no known allergy. The physical examination was not very helpful and did not find any palpable breast lesion besides a 1-cm left axillary lymphadenopathy. Breast screening revealed a solid, poorly delineated structure of 11 mm. Biopsies were taken and revealed a NOS grade II invasive carcinoma, triple negative, with a Ki-67 proliferation index of 15%. The axillary cytology was positive. Faced with this atypical presentation, a skin biopsy was performed on the bruise in order to exclude skin invasion. Histology showed the presence of carcinomatous lymphatic dermal emboli which could correspond to a mammary origin as well as extravasation of blood in the dermis explaining this ecchymotic aspect. Bone scintigraphy found discrete uptake in the rib cage, spine, and pelvis, suspicious in this context, but a benign origin could not be ruled out. Neoadjuvant chemotherapy was initiated before mastectomy and left axillary node dissection. It was an atypical and rare clinical presentation of advanced breast cancer with no similar case found in the literature. Usually, the presence of emboli with carcinomatous cells obstructing the lymphatic vessels is related to inflammatory breast cancer or carcinomatous mastitis. The authors nevertheless point out that although the presence of tumor emboli in the dermal lymphatic vessels is favorable to the diagnosis, it is not required. In addition, dermal lymphatic invasion without a typical clinical presentation is not sufficient to confirm the diagnosis of carcinomatous mastitis. An important diagnostic criterion is the rapidity of aggravation of the symptoms, which, even if it was not obvious in our case, was present with progressive evolution of the skin lesion over several weeks. The skin lesion of our patient could also make us suspect a primary breast angiosarcoma. This possibility was quickly eliminated in the absence of vascular tumor proliferation on the various biopsies. Any acute purpura is a serious disease to be diagnosed urgently, and a skin biopsy is indicated.