Cardiac pseudotumor due to focal hypertrophic cardiomyopathy

Imaging description Focal left ventricular hypertrophy is a variant phenotype of hypertrophic cardiomyopathy (HCM) usually described as involvement of < 2 cardiac segments. Focal HCM can have a mass-like appearance, simulating tumors (Figures 4.1 and 4.2). On cardiac MRI (CMR), mass-like HCM will generally be isointense to adjacent normal myocardium on dark blood spin echo T1-and T2-weighted images and bright blood steady-state free precession (SSFP) sequences. Occasionally, foci of an increased T2-weighted signal can be seen in hypertrophied segments on either dark blood or SSFP sequences, which will be mid-myocardial and patchy. On tagging images, displacement and deformation of tag lines will occur in both normal and hypertrophied myocardium due to myocyte contraction, although reduced contractility may be seen in thickened regions. First-pass perfusion sequences will show homogeneous signal intensity and perfusion characteristics similar to adjacent myocardium. Delayed enhancement has been reported in 45–80% of patients with HCM and usually involves the thickest myocardium. The delayed enhancement pattern is typically patchy and mid-myocardial; however, it can be transmural in advanced cases.Importance Focal HCM can have a mass-like appearance and irregular delayed enhancement that may lead to incorrect diagnosis of a cardiac tumor such as metastasis, lymphoma, fibroma, or rhabdomyoma. This can lead to patient anxiety, inappropriate biopsies, or even surgery.Typical clinical scenario HCM is the most common primary genetic disease of the heart and has a prevalence of 1:500 in the general population. In a large study of 333 individuals with HCM, 12% of patients had the focal pattern of hypertrophy. Patients with a focal pattern of HCM may be initially detected by echocardiography, which can lead to further evaluation by cardiac MRI. Patients are often asymptomatic or may have symptomatic left ventricular outflow tract obstruction due to septal wall hypertrophy and/or systolic anterior motion of the anterior mitral valve leaflets.Differential