Metastatic breast cancer to uterine leiomyoma: case report

Breast cancer is not only considered as the most common cancer in women but also is known as the second cause of death among them. One of the main causes of death in breast cancer patients is metastasis to different organs such as lymph nodes, bones, lung, liver, brain or other parts of the body. Metastasis to genital organs especially uterus is rare and a few cases are reported.

In this report we present a case of invasive ductal breast carcinoma metastasizing to a uterine leiomyoma in a 52 year old woman who was admitted to Imam Khomeini Hospital, Tehran, in September 2013, diagnosed and treated by modified radical mastectomy of the right breast six years ago. Currently, she presented with complaint of persistent abnormal uterine bleeding for which hysterectomy was performed. The histopathologic examination of the uterine specimen revealed a focus in the myometrial wall composed of spindle cell proliferation without signs of atypia which was accompanied by epithelial glandular structures with cells containing hypochromatic nuclei embedded in a desmoplastic stroma. Considering the history of invasive ductal breast carcinoma in this patient, the diagnosis of stromal nodule or metastasis from a breast origin was suggested as the main differential diagnosis. The Immunohistochemical study performed with different markers showed positivity for GCDFP15 staining confirming metastasis from the breast carcinoma.

Although metastasis of breast cancer to the genital organs is an uncommon event, breast carcinoma is still considered the second source of extragenital malignant metastasis to the uterus. Overall, the most popular sites for metastasis of breast carcinoma to the female reproductive system include the ovaries and the uterine cervix. The uterine corpus is the least common site involved. In this regard metastasis to a uterine leiomyoma is a rare event.