Colonic Metastasis from Bronchogenic Carcinoma Presenting as Anemia

Abstract

Purpose: A 67-year-old man presented to the hospital with anemia, abdominal pain and constipation. The clinical examination was unremarkable, except for minimally guaic positive stool. Initial colonoscopy showed a 3 mm lesion at the splenic flexure. Biopsy showed invasive carcinoma with moderately differentiated gland like structures, unlikely to be a primary colonic adenocarcinoma. Immunohistochemical stains were done that were CK7, CK17 positive and CK 20 negative, suggesting a pancreatobiliary or lung primary lesion. Subsequently the patient had a chest CT which revealed a right upper lobe lung mass. He had no evidence of significant lesions elsewhere. The bronchial biopsy revealed an undifferentiated large cell carcinoma of the lung. The patient underwent chemotherapy. Follow-up colonoscopy,9 months later, was normal. Repeat chest CT showed an increase in the size of the lung mass with a new liver lesion. Metastatic lesions to the colon are rare and can pose diagnostic and management difficulties. The malignancies known to cause secondaries in the colon are stomach, breast, ovary, cervix, kidney, lung, bladder, prostate, and melanoma. The usual presentation is with multiple metastatic deposits, but can present as solitary lesion. Colonic metastases from lung cancer may present clinically or as a finding at colonoscopy. Clinically they present with symptoms of colonic obstruction, lower gastrointestinal bleed (occult or massive), weight loss, anemia, bowel perforation, or gastrointestinal fistula. The usual presentation is after the diagnosis of the primary lesion, but can occur synchronously or before the diagnosis of the primary, as in our patient. The lung cancer with intestinal metastasis has been reported to have poor prognosis. The treatment modalities depend on the nature of presentation and extent of the disease. The colonic lesions complicated by obstruction, bleeding, or perforation has to be treated before the assessment of the lung lesion. Depending on the extent of the disease, the treatment options are a ‘curative resection’, palliative procedure (resection or stoma), or chemotherapy. The ‘curative resection’ (resection of the colonic and lung lesions), in selected patients, is reported to have survival advantage. Bronchogenic carcinoma rarely causes synchronous or metachronous metastases in the colon. In those cases, the treatment options are a ‘curative resection’, palliative procedure, or chemotherapy, depending on the extent and differentiation of the tumor. In selected cases, the ‘curative resection’ has survival advantage.