[Simultaneous bilateral breast carcinoma--case study and review of primitive bilateral breast cancer].

Bilateral breast cancer is uncommon and difficult to define because it may manifest as simultaneous, synchronous or metachronous tumours. The true clonal origin and biologic behaviour are still controversial. Following a right breast contusion, bilateral breast tumours were diagnosed in a 74 old female patient; the left one, neglected for 3 years, typically scirrous; the right one with cystic, pseudo-inflammatory appearance. Sonography and fine-needle cytology concluded: left, carcinoma (T3bN1Mx); right, benign nodule with traumatic hematoma. Three sessions of chemotherapy were followed by simultaneous left Madden mastectomy and right simple mastectomy (frozen sections negative for malignancy). Histopathology: left, invasive lobular carcinoma (ypT4N0Mx); right, micropapillary invasive carcinoma mixed with adenoid cystic carcinoma. After another 3 chemotherapeutic sessions, right axillary lymphadenectomy was performed. Both lesions were evaluated by immunohistochemistry and the TNM pathological classification was reconsidered; left, ypT4N1Mx; right, ypT3N0Mx. Considering the natural history, histopathological and immunohistochemical patterns of the two tumours, these seem to be distinct but shearing a common favourable biologic behaviour. No genetic studies were performed in the absence of specific risk factors. Based on clinical, epidemiologic, morphologic and genetic evidence, bilateral breast cancers (synchronous or metachronous) are considered to be a special evolutive entity of breast cancer. Our case suggests that, in the absence of risk factors for bilaterality of breast carcinoma: description of bilateral breast cancers based on diagnostic chronology of the two tumours is arbitrary; they may occur sporadically and have independent evolution; their biology rather resembles a multiple primitive malignancy than a true bilateral breast cancer.