Precision Monitoring in a Sepsis Mimic: A Case Report of Idiopathic Capillary Leak Syndrome in the Surgical ICU.

Idiopathic Capillary Leak Syndrome (ICLS), also known as Clarkson's disease, is a rare yet potentially life-threatening disorder of unknown etiology. It is a clinical condition that is frequently overlooked, but represents a severe and potentially fatal illness, characterized by fluid extravasation into the interstitial space, resulting in hemoconcentration, generalized edema, effusions, and hypotension. Owing to the similarity of its symptoms to those of other conditions, ICLS is often underdiagnosed, thereby posing a challenge for patient management. We report a complex case of a 69-year-old patient who presented with shock secondary to a necrotic cecal tumor and was ultimately diagnosed with ICLS. This case underscores the diagnostic challenges, the need for awareness and need for precision monitoring in differentiating ICLS from other causes of shock and emphasizes the critical importance of early recognition and appropriate therapeutic intervention. Additionally, a review of the current understanding of ICLS pathophysiology, diagnostic criteria, and treatment strategies, based on existing evidence, is provided.