Unintentional weight loss (UWL) is a common presenting symptom with a wide differential diagnosis. Causes may be organic (e.g., malignancy or gastrointestinal disease) or inorganic (e.g., psychosocial). The purpose of this review is to provide a guide for radiologists and other clinicians to understand the imaging modalities and laboratory studies involved in the diagnosis and treatment of UWL and the evidence supporting their routine use. Cases illustrating both common and uncommon causes of UWL are presented to emphasize both the breadth of pathology that may cause UWL as well as the importance of a multi-modality diagnostic approach. Imaging studies are crucial in the diagnosis of unintentional weight loss, particularly with regard to evaluating for the presence of malignancy. It is important for both the radiologist and other clinicians to understand the relative prevalence of the various causes of UWL and the utility of different imaging modalities in diagnosis and management.
Keywords: Multimodality; Multispecialty; Unintended weight loss; Unintentional weight loss.