Introduction: AL amyloidosis results from deposition of misfolded immunoglobulin light chains in various organs, with cardiac involvement occurring in approximately 60-70% of cases. Cardiac amyloidosis typically presents with heart failure symptoms and distinctive echocardiographic features including increased wall thickness, "sparkling" myocardium appearance, and restrictive physiology. While commonly associated with multiple myeloma, oligosecretory variants can pose diagnostic challenges due to minimal or absent monoclonal protein secretion in serum.

A 43-year-old female presented with progressive palpitations, dyspnea, fatigue, and peripheral edema. Initial evaluation by cardiology revealed significant cardiac abnormalities prompting comprehensive investigation.

Echocardiography demonstrated characteristic findings highly suggestive of cardiac amyloidosis: concentric left ventricular hypertrophy with "sparkling" myocardium appearance, restrictive diastolic pattern, biatrial enlargement, moderate tricuspid regurgitation, and mild pulmonary hypertension. The constellation of findings was inconsistent with hypertensive heart disease, raising suspicion for infiltrative cardiomyopathy.

Given the typical echocardiographic appearance, the patient was referred to hematology for amyloidosis evaluation. Laboratory assessment revealed elevated inflammatory markers (CRP: 59-74 mg/L) but notably, serum protein electrophoresis showed no distinct M-band. However, serum immunofixation was positive only for lambda light chains with negative IgA, IgG, and IgM, suggesting an oligosecretory plasma cell disorder.

Bone marrow biopsy revealed 40% plasma cell infiltration with immunophenotype showing CD38(+), CD56(+), and CD19(-) with lambda light chain restriction. Critically, Congo red staining was positive, confirming amyloid deposition and establishing the diagnosis of AL amyloidosis. Cytogenetic analysis by FISH was negative for high-risk abnormalities including p53 deletion, RB1 deletion, t(11;14), and t(4;14).

Additional imaging revealed multisystem involvement: chest CT showed ground-glass opacities in lower lobes with reactive mediastinal lymphadenopathy, while abdominal ultrasound demonstrated grade 1 hepatosteatosis, minimal splenomegaly, and mild ascites, consistent with systemic amyloid deposition.

The patient's medical history was notable for appendiceal mucinous neoplasm in 2022, raising questions about potential relationships between these conditions.

Clinical presentation included progressive heart failure symptoms with peripheral edema, confirming cardiac involvement as the primary manifestation.

This case illustrates several important clinical aspects of AL amyloidosis. The presentation in a 43-year-old patient is relatively uncommon, as AL amyloidosis typically affects older adults with median age around 65 years. The cardiac-predominant presentation with characteristic echocardiographic findings enabled early recognition and appropriate referral.

The oligosecretory nature of the underlying plasma cell dyscrasia initially complicated diagnosis, as conventional serum protein studies were unrevealing. This emphasizes the importance of comprehensive light chain analysis in suspected cases, as oligosecretory variants can account for up to 15% of cases.

The "sparkling" myocardium appearance on echocardiography, while not pathognomonic, represents a classic finding in cardiac amyloidosis resulting from increased acoustic reflectance of amyloid-infiltrated myocardium. Combined with restrictive physiology and biatrial enlargement, these findings strongly suggest amyloid cardiomyopathy.

The multisystem involvement demonstrated by imaging studies indicates advanced disease requiring prompt treatment initiation. Cardiac amyloidosis carries poor prognosis without treatment, with median survival often less than one year in symptomatic patients.