Intraluminal Small Bowel Metastasis From Primary Lung Cancer

Lung cancer is the leading cause of cancer-related death worldwide, with frequent metastases to the brain, liver, adrenal glands, and bone. The incidence of intraluminal small bowel metastases of the lung is extremely rare and poorly documented within the literature. Few case studies have been published since the late 1980s and early 1990s. However, little is known about this rare form of metastasis. Small bowel metastatic disease has atypical symptoms that mimic a variety of other diseases; as a result, signs and symptoms may be overlooked until the disease has progressed to a late stage. Signs of small bowel obstruction, symptomatic anemia, abdominal pain, and peritonitis are commonly reported signs and symptoms. Various modalities can be utilized for the workup of suspected small bowel metastasis, including positron emission tomography, computed tomography, and various forms of endoscopy. The prognosis for lung cancer patients with intestinal metastases is poor, with many only surviving months to a few years after diagnosis. Therefore, it is critical to consider small bowel masses as a differential diagnosis in a patient with primary lung cancer who demonstrates clinical signs consistent with symptomatic anemia secondary to gastrointestinal (GI) bleeding, peritonitis, or small bowel obstruction. We report an unusual case of intraluminal and fungating small bowel masses in a patient who had previously undergone lung resections and chemo-immunotherapy. She was diagnosed with non-small undifferentiated carcinoma with tumor necrosis over 12 years before disease recurrence in the bilateral lungs, right adrenal gland, bone, and small bowel. The discovery of the small bowel metastases occurred while undergoing treatment for advanced-stage disease. At this time, she completed chemo-immunotherapy and remained on maintenance immunotherapy. The patient also underwent a partial right adrenalectomy and radiotherapy to the right adrenal gland. Given that she was experiencing symptomatic anemia and further workup indicated that the GI masses were causing her anemia, she underwent palliative small bowel resection of the masses. The pathology results demonstrated that the masses originated from her primary lung cancer, confirming metastatic disease to the small bowel.