Case report and literature review: Metastatic lobular carcinoma of the breast an unusual presentation.

Introduction: Invasive lobular carcinoma is the second most common type of invasive breast carcinoma (between 5% and 15%). The incidence of invasive lobular carcinoma has been increasing while the incidence of invasive duct carcinoma has not changed in the last two decades. This increase is postulated to be secondary to an increased use of combined replacement hormonal therapy. Patients with invasive lobular carcinoma tend to be slightly older than those with non-lobular invasive carcinoma with a reported mean age of 57 years compared to 64 years. On mammography, architectural distortion is more common and microcalcifications less common with invasive lobular carcinoma than invasive ductal carcinoma. The incidence of extrahepatic gastrointestinal (GI) tract metastases observed in autopsy studies varies in the literature from 6% to 18% with the most commonly affected organ being the stomach, followed by colon and rectum. Gastric lesions seem to be slightly more frequent, compared to colorectal lesions (6-18% compared to 8-12%, respectively).
Presentation of Case: We present the case of a 70-year-old woman who was referred to our institution with a concurrent gastric and rectal cancer that on further evaluation was diagnosed as metastatic invasive lobular carcinoma of the breast. She has a stage IV clinical T3N1M1 left breast invasive lobular carcinoma (ER positive at 250, PR negative, HER-2/neu 1+ negative) with biopsy proven metastases to left axillary lymph nodes, gastric mucosa, peritoneum, rectal mass, and bone who presented with a partial large bowel obstruction. She is currently being treated with weekly intravenous paclitaxel, bevacizumab that was added after her third cycle, and she is also receiving monthly zoledronic acid. She is currently undergoing her 12-month of treatment and is tolerating it well. Discussion Breast cancer is the most common site-specific cancer in women and is the leading cause of death from cancer for women aged 20-59 years. It accounts for 26% of all newly diagnosed cancers in females and is responsible for 15% of the cancer-related deaths in women.(9) Breast cancer is one of the most common malignancies that metastasize to the GI tract, along with melanoma, ovarian and bladder cancer.
Conclusion: We present one of the first reports of metastatic lobular breast cancer presenting as a synchronous rectal and gastric tumors. Metastatic lobular carcinoma of the breast is a rare entity with a wide range of clinical presentations. A high level of suspicion, repetition of endoscopic procedures, and a detailed pathological analysis is necessary for early diagnosis, which might help to avoid surgical treatment due to incorrect diagnosis. Patients with a history of breast cancer who present with new gastrointestinal lesions should have these lesions evaluated for evidence of metastasis through histopathologic evaluation and immunohistochemical analysis. Differentiating between a primary GI lesion and metastatic breast cancer will allow initiation of appropriate treatment and help prevent unnecessary operations.