Bilateral male breast cancer: a case presenting with synchronous invasive lobular carcinoma and invasive ductal carcinoma

Synchronous bilateral male breast cancer is a very rare entity and invasive lobular carcinoma is less common in male breast cancer (MBC) than in female breast cancer (FBC).A 51-year-old man presented with a palpable mass in the left breast was finally diagnosed synchronous bilateral MBC, one an invasive lobular carcinoma and the other an invasive ductal carcinoma.It remains a matter of debate whether invasive lobular carcinoma has better or worse outcome than invasive ductal carcinoma, so that clinicopathological characteristics of tumors are used to evaluate the risk of recurrence.In our case, an unusually small invasive ductal carcinoma with a low level of proliferation had already developed many axillary lymph node metastases in spite of dire clinicopathological characteristics of the invasive lobular carcinoma of the left breast determined during the first treatment, while the invasive ductal carcinoma of the right breast was thought to have developed distant metastasis.We report the first case of synchronous bilateral MBC, one an invasive lobular carcinoma and the other an invasive ductal carcinoma, and discuss about the unusual clinicopathological characteristics of these two tumors.