Imaging features of catastrophic antiphospholipid syndrome : Massive saddle pulmonary embolism with subsequent complete resolution.

Catastrophic antiphospholipid syndrome (CAPS) is a rare thrombotic disorder that can present with distinctive imaging features. Recognition of these imaging patterns is critical for timely diagnosis and management. We report the imaging findings in a 27-year-old woman presenting with acute dyspnea. Computed tomography pulmonary angiography (CTPA) revealed a large saddle embolus at the main pulmonary artery bifurcation with bilateral extension, accompanied by right ventricular dysfunction on echocardiography. The constellation of imaging findings-massive central thrombus burden, right heart dysfunction indices (RV/LV ratio 1.3, TAPSE 13mm), and absence of deep venous thrombosis-prompted consideration of an underlying thrombophilic disorder. Subsequent workup confirmed CAPS with multiorgan involvement. Following treatment with thrombolysis, corticosteroids, and plasmapheresis, follow-up CTPA at three months demonstrated complete thrombus resolution with normalization of cardiac parameters. This case illustrates the characteristic imaging appearance of CAPS-related massive pulmonary embolism and emphasizes the need to recognize high-risk features that suggest underlying systemic thrombophilia. Multimodality imaging is essential for diagnosis, risk stratification, treatment monitoring, and documenting complete resolution.