Gastrointestinal: Positron emission tomography–computed tomography imaging of multifocal intestinal metastasis from primary lung cancer

Abstract

A 77-year-old man had a history of coronary artery bypass graft, prostate cancer with total prostatectomy, ulcerative colitis with total colectomy and ileal-to-rectal anastomosis, and pleural metastatic lung adenocarcinoma treated with radiation therapy and just concluding cycle 8 of Pembrolizumab therapy. He had a restaging F-18 FDG positron emission tomography–computed tomography (PET/CT) showing an interval enlargement of the previously documented right lung pleural-based lesion with eight new tracer-avid masses scattered throughout the small intestines (Fig. 1). Contemporary to the PET/CT imaging, the patient experienced poor oral intake, nausea, vomiting, and diarrhea. Subsequently, the patient’s gastrointestinal symptomatology progressed to an obstructive syndrome depicted by CT as intussusception from a right intestinal mass (Fig. 2b). Surgery and pathology confirmed the presence of multifocal small bowel metastases from primary lung cancer (Fig. 2d–f). The postoperative course was burdened with numerous complications leading to the patient’s demise. Primary lung cancer has a propensity to metastasize to the lymph nodes, adrenal glands, liver, bones, and brain. The occurrence rate of gastrointestinal (GI) metastasis is low about 0.37– 1.7% clinically. Among different histological types of lung cancer, the decreasing order of GI tract metastasizing lung primary is as follows: large cell carcinoma, squamous cell carcinoma, and adenocarcinoma. Concerning the GI tract involvement, the most frequent location is the small intestines followed by the colon and rectum, stomach, and esophagus. Clinical symptomatology includes abdominal pain, obstructive bowel syndrome from mass effect or intussusception, GI bleed, and perforation. The clinical manifestations, mentioned earlier, are usually reasons prompting imaging evaluation and demonstration of GI tract involvement from lung cancer. Lung cancer with GI tract dissemination carries a poor prognosis. CT features focal bowel wall thickening, nodular or polypoid mass with or without ulceration, bowel intussusception, and signs of hemorrhage and perforation. PET/CT provides a more accurate staging of lung cancer and related regional and distant metastasis based on the metabolic behavior of the primary and secondary lesions. Rare is the instance of multifocal intestinal metastasis as illustrated by the presented case with PET/CT imaging.