Japan's Imperial Household Agency says Empress Emerita Michiko has been diagnosed with a relatively early stage of breast cancer. Agency officials say that it's unlikely that the cancer has spread to other organs.
The agency says a tumorous mass was found in the mammary gland of her left breast during a health checkup last month.
The diagnosis was made on August 2 after a tissue examination at the Imperial Household Hospital.
An additional test will be conducted to decide the best treatment for her condition.
She is expected to undergo an operation in or after September.
The agency says she has had regular checks on her mammary glands over the past decade or so, and no irregularities were found in the past 12 months.
It also says the Empress Emerita has lost weight since around the abdication of Emperor Emeritus Akihito at the end of April.
The couple is due to spend the holidays in the resort towns of Karuizawa and Kusatsu, both north of Tokyo, later this month.
The agency officials say the Empress Emerita has been under stress due to her busy schedule. They say she will have surgery after she regains her strength during the vacation.