The role of CMR in Rosai-Dorfman disease

Description of Clinical Presentation: A 54-year-old woman with a history of Rosai-Dorfman disease (RDD) diagnosed in 2020 presented for a routine haematology follow-up with chest pain, worse when lying down, and dyspnoea. Her ECG demonstrated complete heart block, and her brain natriuretic peptide (BNP) was 1142 pg/mL. She was not on active treatment but had previously received local radiotherapy for non-malignant pelvic lesions. Cardiovascular magnetic resonance (CMR) was performed to evaluate for possible RDD-related cardiac involvement or other myopathy contributing to heart block.

Diagnostic Techniques and Their Most Important Findings: CMR demonstrated a normal left ventricular (LV) size with preserved systolic function (LVEF 54%). The right ventricle (RV) showed normal indexed end-diastolic volume (62 ml/m²) and good systolic function.

An irregular intracardiac mass was identified within the interatrial septum, extending into the interventricular septum and surrounding the mitral and aortic valve annuli. The mass measured 37 × 23 mm and appeared hyperintense on Half-Fourier Acquisition Single Shot Turbo Spin Echo (HASTE) sequences, while showing homogeneous, intermediate signal intensity on balanced Steady-State Free Precession (b-SSFP) sequences (Figure 1).

Turbo Spin Echo (TSE) sequences in four-chamber and short-axis views were acquired for further characterisation. On T2-weighted images with spectral fat suppression, the mass demonstrated high signal intensity. On T1-weighted images, it appeared mildly hyperintense without signal change after fat suppression (Figure 2).

Quantitative mapping revealed elevated T2 values within the mass (80 ms; normal < 55 ms) and normal myocardial T2 values. Native T1 mapping showed elevated signal within the mass (1251 ms; normal 890–1035 ms), while myocardial T1 values remained within the normal range.

Early and late gadolinium enhancement demonstrated heterogeneous enhancement of the mass, with no evidence of myocardial fibrosis, infiltration, or infarction (Figure 3).

The lesion’s location around the aortic root and basal septum likely explains the patient’s presentation with complete heart block at admission, a recognised feature of this pathology.

Learning Points from this Case: CMR findings are consistent with an extra-nodal manifestation of RDD/non-Langerhans histiocytosis. Cardiac involvement in RDD is extremely rare, reported in fewer than 1% of cases, and poses important diagnostic and management challenges. In this setting, CMR plays a pivotal role not only in excluding cardiac thrombi but also in providing detailed tissue characterisation, assessing the extent of the mass, detecting associated fibrosis, and identifying the involvement of adjacent cardiac structures and vessels. By integrating anatomical and functional information, CMR offers a comprehensive evaluation that is invaluable for guiding clinical decision-making, patient management, and treatment planning.

Figure 1: Four chamber HASTE (A) and b-SSFP (B)
Figure 2: Short Axis T1-weighted (A) and Short Axis T2 Fat Saturation (B)
Figure 3: Four chamber (A) and Short Axis (B) late gadolinium enhancement