Duodenal metastases from lung adenocarcinoma causing gastrointestinal bleeding: a rare aetiology

Gastrointestinal metastases from primary lung adenocarcinoma are rare, with only a few reported cases of gastrointestinal bleeding caused by such metastases. Among the cancers that most commonly spread to the gastrointestinal tract are lung, breast, kidney and melanoma. Symptoms can vary, but patients are usually asymptomatic, presenting in advanced stages. We present a case of gastrointestinal bleeding secondary to a duodenal ulcer found to be a metastatic lesion from primary lung adenocarcinoma. Although the diagnosis can be challenging, especially when no lung malignancy is known yet, immunochemistry can be used to differentiate between primary gastrointestinal cancer and lung cancer metastasis.