Title: An Unusual Case of Metastatic Breast Cancer Masquerading as Gallstone Pancreatitis
Author(s): Bryce Straffin, DO; Taylor Abraham, MD
Email: bstraffin@mercy.com
Introduction: Metastasis to the gastrointestinal system from breast cancer is well-known but rare. Invasive lobular carcinoma (ILC) is more likely to metastasize to the gastrointestinal system, especially the stomach, but is still exceedingly rare at 4%. The usual sites of breast cancer metastasis are the lung, liver, bone, and brain. This case report describes an atypical presentation of breast cancer starting as gallstone pancreatitis, leading to the diagnosis of gastric outlet obstruction from metastatic triple-negative breast cancer (TNBC).
Case Report(s): A 58-year-old Black female presented with epigastric pain and intractable nausea for one week. Laboratory workup and CT scan led to the diagnosis of gallstone pancreatitis, and she underwent a laparoscopic cholecystectomy. It was noted during the cholecystectomy that the duodenum and stomach appeared distended despite continuous suction on the nasogastric tube. ERCP showed an edematous, strictured pylorus and duodenum, causing gastric outlet obstruction.
During the initial workup, we saw that her left upper extremity was edematous compared to her right, and she was complaining of left breast discomfort and swelling. At an outpatient clinic appointment before this hospitalization, she had x-rays, an ultrasound, and a CT scan of the arm, which did not lend a diagnosis. A mammogram one year prior showed a breast mass, and a biopsy revealed a fibroadenoma. The radiologist deemed this concordant with the imaging at that time.
Pathology of the gallbladder was acute on chronic cholecystitis. Pathology from the breast mass and left axillary lymph node was poorly differentiated triple-negative invasive ductal carcinoma (IDC). The biopsies of the pylorus done during the ERCP also showed TNBC.
Discussion: The most common malignancy in women in the United States is breast cancer. Approximately 290,560 persons have been diagnosed with breast cancer, and 43,780 will succumb to this disease in 2022. Our patient had invasive ductal carcinoma, which is the most common subtype at 70-80% of all breast cancers. The five-year survival is 99% when the cancer is only in the breast and 86% if there is locoregional spread. However, five-year survival decreases to 28% when metastasis has occurred.
TNBC accounts for about 15% of invasive breast cancers. It is more common in Black than White patients. The mortality rate in Black women is often higher, and they are at least twice as likely to be Stage III or IV at the time of diagnosis compared to White women for any breast cancer. The incidence of TNBC is higher among Black women compared to White women.
Metastatic breast cancer to the stomach is rare. A retrospective single-center study of 13 patients with metastatic breast cancer to the stomach by Hong et al. found that 7 were ILC and 6 were IDC. Of these, 12 (92%) were ER+. No patients were triple negative. Notably, only 2 of the 13 initially presented with stage IV disease. Taal et al. determined that out of 51 patients with gastric metastasis, 36 (70%) were ILC, and only 10 (19%) were IDC. The study did not test for PR or HER2 markers but reported that 26 were ER+. Five patients were stage IV on the initial clinical workup.
This is only the second case in the literature with a similar presentation and triple-negative metastatic disease. A majority of gastrointestinal metastatic disease is from ER+ disease.
