Epicardial Amyloidoma Mimicking Secondary Cardiac Lymphoma: A Sneeze Away From the Diagnosis.

BACKGROUND: Cardiac masses may represent a wide spectrum of neoplastic, inflammatory, and infiltrative diseases. Localized amyloid deposition (amyloidoma) is a rare entity that can closely mimic malignant cardiac infiltration. CASE SUMMARY: A man with indolent B-cell lymphoma and monoclonal gammopathy was referred after incidental electrocardiogram abnormalities. Echocardiography showed an epicardial mass. Cardiac magnetic resonance demonstrated marked enhancement and increased extracellular volume, suspicious for secondary cardiac lymphoma or Erdheim-Chester disease. Positron emission tomography and bone scintigraphy were nondiagnostic. Surgical biopsy was performed and revealed Congo red-positive amyloid deposition associated with lambda-restricted plasma cells and a CD5-positive B-cell infiltrate. DISCUSSION: This case illustrates a rare epicardial amyloidoma mimicking malignant cardiac infiltration. It highlights the diagnostic challenges of atypical amyloid light-chain amyloidosis and the importance of early hematologic evaluation and histopathologic confirmation in patients with inconclusive imaging findings. TAKE HOME MESSAGES: Localized amyloid deposition can be a rare presentation of amyloid light-chain amyloidosis. Comorbid or secondary conditions should not be overlooked.