Figure 2. A large homogenous mass like thickness in RA (4.87 *1.66 cm), abnormal thickening post IAS is seem to be infiltrative process
The patient’s younger brother, currently 27 years old, was found to be homozygous for a pathogenic variant in the SLC29A3 gene. Laboratory results showed elevated erythrocyte sedimentation rate (ESR) and reactive protein (CRP) levels. Echocardiography revealed a large heterogeneous mass-like thickness in the right atrium. CMR confirmed an infiltrative mass in the RA roof and atrioventricular (AV) groove with the encasement of the RCA and SVC (Figure 3 A-E). Later, EDC emerged as the leading differential diagnosis based on MRI tissue characterization criteria.
Furthermore, a CT scan showed mild abdominal aortic wall thickening, bilateral renal cortical and peri-renal soft tissue infiltration, and mild diffuse osteopenia and wedge deformity of the thoracolumbar vertebra, all consistent with EDC. Kidney biopsy revealed mixed inflammatory cell infiltration containing some histiocytes, supporting the diagnosis of non-Langerhans cell histiocytosis.