Chylothorax as an unusual manifestation of transthyretin cardiac amyloidosis: a case report

Background Amyloidosis is a multi-organ disease of emerging significance in the field of cardiology. Chylothorax, a specific form of pleural effusion characterized by lymphatic fluid accumulation in the pleural cavity, is an extremely rare manifestation of amyloidosis. Notably, only five cases of chylothorax related to cardiac amyloidosis have been reported worldwide, all in amyloid light chain (AL) amyloidosis. No cases have been documented in amyloid transthyretin (ATTR) amyloidosis. Furthermore, elevated levels of serum carbohydrate antigen (CA) 125 have been associated with a poor prognosis in patients with AL cardiac amyloidosis.Case summary We report the case of an 85-year-old Austrian man with pronounced left ventricular hypertrophy, monoclonal gammopathy, and a history of atrial fibrillation. Further examinations, including myocardial biopsy, confirmed the diagnosis of ATTR cardiac amyloidosis. A significant right-sided pleural effusion was also observed. Thoracocentesis diagnosed chylothorax, confirmed by lymphangiography. Elevated CA 125 levels were found in both serum and pleural fluid, with no other findings suspicious for malignancy. The patient underwent a short break in oral anticoagulation and received prophylactic low-molecular-weight heparin for myocardial biopsy, thoracocentesis, and lymphangiography. However, they died a few days later due to an embolic stroke.Discussion At this time, we can only speculate about the pathomechanism of chylothorax development in the context of amyloidosis. We recommend further investigation of similar cases to deepen understanding of the underlying causes and identify potential treatment strategies. Additionally, the utility of CA 125 as a prognostic marker in ATTR amyloidosis needs further investigation.