Lung Manifestations of Metastatic Duodenal Adenocarcinoma: A Case Report.

Pulmonary lymphangitic carcinomatosis (PLC) is a rare condition characterized by malignant infiltration within the lymphatic system. It most often arises from adenocarcinoma of the breast, lung, or pancreas. This rare diagnosis often evades detection due to diagnostic challenges, unknown pathogenesis, and indolent presentation. Villous adenoma of the duodenum is also an exceedingly rare malignancy that is often mistaken for various pancreatic pathologies. To our knowledge, we describe the first case of PLC secondary to biopsy-confirmed villous adenocarcinoma of the duodenum in a 56-year-old male who presented with dyspnea, cough, and weight loss. This case illustrates how an indolent-appearing duodenal lesion can manifest as aggressive pulmonary metastasis, emphasizing the need for clinicians to maintain a broad differential when evaluating diffuse pulmonary disease and the importance of integrating radiographic, histopathologic, molecular, and multidisciplinary tools to identify rare metastatic origins.