Mistletoe Sign in a Cardiac MRI in a patient with Multiple Myeloma

Description of Clinical Presentation: We present the case of a 75-year-old female patient with a history of IgG Lambda multiple myeloma with interstitial and multifocal infiltration due to plasma cell neoplasia with lambda chain restriction, presenting multiple lytic lesions in the dorsal and lumbar vertebral bodies; she also has a history of coronary stent placement in the right coronary artery, chronic kidney disease and acute pulmonary thromboembolism . The patient also has a history of chronic myopericarditis with pericardial effusion and thickening of the visceral pericardium. Another finding was the presence of mitral valve endocarditis. The patient began to show signs of heart failure, so the hematology department requested a cardiac MRI for functional and structural assessment.

Diagnostic Techniques and Their Most Important Findings: The different sequences obtained are reviewed and a functional assessment is performed without significant alteration of the right ventricular ejection fraction or left ventricular ejection fraction. Diffuse thickening of the pericardium was observed, reaching a thickness of 4.8 mm. There is moderate mitral regurgitation. The MOLLI sequences identified a slight increase in native T1 associated with segmental hypertrophy, a finding that could correspond to amyloid infiltration. Late enhancement sequences identified subendocardial enhancement related to an ischemic pattern at the apex. Finally, a soft tissue nodular image was observed surrounding 360° of the right coronary artery in its middle third (Mistletoe sign).

Learning Points from this Case: This is a very interesting case due to its complexity; it involves a patient with a history of multiple myeloma in whom, given the suspicion of elevated native T1 in MOLLI sequences associated with clinically segmental thickening, systemic amyloidosis was suspected; findings of ischemic heart disease in the apex and the presence of a right coronary stent in which a nodular image of soft tissue can be seen circumferentially bordering the right coronary artery (“Mistletoe sign”). This sign has been described in patients with retroperitoneal fibrosis and IgG4 disease; however, the patient's clinical context does not support these diagnoses, which opens up the possibility of some connection with multiple myeloma or amyloidosis, which has not been described.

Acquisition in black blood in which diffuse pericardial thickening can be seen.
Delayed enhancement image in a three-camera view showing delayed enhancement at the apex
Four-chamber cine-resonance image showing diffuse pericardial thickening and, at the level of the right atrioventricular groove, a nodular image of soft tissue completely surrounding the circumference of the right coronary artery (Mistletoe sign).