Metastases in the gastrointestinal tract are uncommon. In autopsy studies in patients with advanced cancer, fewer than 5% of patients have identifiable metastases in the gastrointestinal tract. These metastases are located in the small bowel, stomach and colon in an approximate ratio of 3:2:1. For metastases in the small bowel and stomach, the most common primary sites are malignant melanoma, breast and lung. For metastases in the colon, common primary sites include the lung and breast. The majority of gastrointestinal metastases are multiple and usually occur in the setting of known metastases in other organs. Single metastases restricted to the gastrointestinal tract appear to be rare. At colonoscopy, some metastases have an unusual polypoid appearance while others are indistinguishable from early colorectal cancer. We report a rare example of an isolated colonic metastasis associated with cancer of the parotid gland.
A 78-year-old man was investigated because of the development of a lump in his neck. Histological evaluation of a fine needle aspirate revealed cancer of the parotid gland. Because of anemia, he was also investigated by colonoscopy. This revealed a polypoid lesion, 10 mm in diameter, in the transverse colon (Fig. 1). The lesion had the appearance of a polypoid adenoma but was harder than a typical adenoma when palpated with biopsy forceps. Furthermore, the polyp had an irregular lobulated surface and, at chromoendoscopy, there was a clear demarcation line that separated the polyp from normal adjacent mucosa. Histological evaluation of colonic biopsies showed a malignant neoplasm with similar features to the primary parotid cancer (Fig. 2). The patient was treated with chemotherapy. Surgical resection for a presumed isolated intestinal metastasis is often appropriate in the setting of malignant melanoma and renal carcinoma but is of uncertain benefit for metastases from other malignant neoplasms.