Metastatic colonic and gastric polyps from breast cancer resembling hyperplastic polyps
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Breast cancer metastasis to the gastrointestinal tract is relatively rare and is generally found when patients complain of symptoms such as gastrointestinal obstruction. Herein, we report a case with metastatic colonic and gastric lesions from breast cancer, with the formation of mucosal polyps which resembled typical hyperplastic polyps.
A 47-year-old woman underwent curable surgery for breast cancer and received standard systemic treatments. Her primary tumor was composed of a mix of invasive lobular and ductal carcinomas. During adjuvant endocrine therapy, she developed multiple colonic metastases, identified by colonoscopy performed as part of a general health check-up. She had no symptoms. Small elevated sessile polyps in the transverse colon and rectum showed histological features of signet-ring cell type adenocarcinoma, similar to the invasive lobular component of the primary breast cancer. During treatments for recurrent disease, she also developed multiple gastric metastases, with the same endoscopic and pathological features as the colonic lesions. Her treatment regimen was switched to oral chemotherapy, and she has since maintained stable disease for nearly 3 years. Multiple bone metastases eventually developed, and she was again switched to another systemic treatment but, to date, has remained free of symptoms.
We emphasize that the endoscopic findings of the metastatic lesions in the colon and stomach in this case highly resembled hyperplastic polyps. Since biopsy is not always performed for hyperplastic polyps in the gastrointestinal tract, we believe that this case report may encourage endoscopists to offer biopsies to the patient who has a history of breast cancer.
KeywordsBreast cancer Lobular carcinoma Colonic metastasis Mucosal metastatic polyp
Human epidermal growth factor receptor 2
Invasive ductal carcinoma
Invasive lobular carcinoma
Selective estrogen receptor modulator
Breast cancer rarely metastasizes to the gastrointestinal (GI) tract, and only 5% of patients with recurrent disease have GI metastasis . Invasive lobular carcinoma (ILC), which is characterized by minimal cell-cell adhesion, is known to more often metastasize to the GI tract than invasive ductal carcinoma (IDC), and this is especially true of ILC of the signet-ring cell type [2, 3].
In making the differential diagnosis of metastatic disease, several immunohistochemical (IHC) markers are useful for identifying breast cancer as the primary tumor. Estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) are often examined, but their expressions are detected in 12–25% and 20% of gastric cancers [4, 5, 6], and in 30–56% and 4–14% of colon cancers [7, 8, 9, 10], respectively. Thus, these examinations are not sufficient, in terms of tissue specificity, for identifying the origin of metastasis. CK7 is often observed in the epithelial layers of breast ducts and the lungs, while intestinal tissues show no expression of this protein [11, 12]. On the contrary, CK20 is often expressed in the large intestine and bile ducts, while it is rarely seen in the breast [11, 12]. Thus, metastatic disease from breast cancer is expected to be CK7-positive and CK20-negative, while the opposite is generally seen in primary colon cancer. GCDFP-15 and mammaglobin are also widely used. GCDFP-15, one of the proteins comprising the walls of benign cysts of the breast, is expressed in 32–47% of breast cancer metastatic lesions [13, 14]. Mammaglobin expression, observed only in breast and skin tissues, is also positive in 42–87% of metastases from breast cancer [13, 14, 15].
GI metastasis is typically found when patients complain of symptoms such as GI obstruction. At this stage, GI tract metastasis of ILC reportedly shows macroscopic findings of linitis plastic in some cases, rather than forming a large, localized, and elevated lesion [16, 17, 18, 19, 20].
Herein, we report a rare case with metastatic colonic mucosal polyps from breast cancer, which had an entirely hyperplastic appearance, and produced no symptoms. Metastasis localized only in the GI mucosa, verified endoscopically  or surgically , is very rare.
Throughout her clinical course, she has remained free of symptoms, suffering neither abdominal pain nor melena.
We could not ascertain whether the metastases represented mucosal lesions if the patient had not undergone a routine health check-up. Otherwise, she might have progressed to a severe condition, such as GI perforation or obstructive ileus. Instead, this patient has been free of symptoms for more than 5 years with adequate systemic therapies against recurrent diseases.
We emphasize that, based on the endoscopic findings, these colonic and gastric metastatic lesions essentially had the appearance of hyperplastic polyps. Since biopsy is not consistently performed for hyperplastic polyps in the GI tract, this case report may encourage endoscopists to offer biopsies to patients with a history of breast cancer. Whether or not this endoscopic appearance indicates early GI metastasis needs to be determined based on further case reports.
YH and TH identified the unusual features of this case. YH wrote the article. TH performed endoscopy and provided all endoscopic images for the article. AA was the principal pathologist and supplied all of the pathology images. YH, HM, and MS were responsible for overall care of the patient. MS critically revised the manuscript for content. All authors read and approved the final manuscript.
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Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
The authors declare that they have no competing interests.
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