Solitary uterine metastasis of invasive lobular carcinoma after adjuvant endocrine therapy: a case report

INTRODUCTION: Solitary uterine metastases from extragenital cancers are very rare. Breast cancer is the most frequent primary site of metastasis to the uterine corpus, with invasive lobular carcinoma more likely to spread to gynecologic organs than invasive ductal carcinoma. CASE PRESENTATION: A 62-year-old postmenopausal Japanese woman was diagnosed with uterine leiomyomata more than 20 years ago and had been managed conservatively until menopause. Seven years prior to her presentation, she was diagnosed with breast cancer and underwent a partial resection of her right breast for stage IIA invasive lobular carcinoma. She underwent adjuvant chemotherapy, radiotherapy, and five years of anastrozole hormonal therapy. She presented with a growing uterine mass. Her tumor marker levels were markedly increased over the course of her follow-up, but a systemic examination revealed only a solitary uterine tumor. She underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. A histopathological examination, including detailed immunohistochemistry, confirmed metastatic invasive lobular carcinoma, infiltrating both her uterine myometrium and fibroid tissue. CONCLUSION: We report a very rare metastatic pattern of invasive lobular carcinoma and demonstrate that gross cystic disease fluid protein-15 and mammaglobin are useful in the diagnosis of metastatic breast cancer.