What is AL amyloidosis?

AL amyloidosis (also called light chain amyloidosis) is a rare condition in which abnormal antibody fragments produced by a small population of bone marrow plasma cells fold incorrectly and deposit as amyloid protein in organs. The deposits damage the affected organs and can be life-threatening, particularly when the heart is involved.

Why it is related to plasma cell disorders. Plasma cells normally produce antibodies. In AL amyloidosis, a small population of plasma cells (less than the amount that defines multiple myeloma in most cases) produces antibody light chains that fold incorrectly and deposit as amyloid. The underlying biology overlaps with multiple myeloma, but AL amyloidosis is its own condition with its own management.

The organ involvement.

Heart: cardiac AL amyloidosis is the most consequential form because it can cause severe heart failure and arrhythmias, and untreated cardiac AL has historically had a poor outlook.

Kidneys: renal AL amyloidosis presents with proteinuria and progressive kidney impairment.

Nervous system: peripheral neuropathy, autonomic neuropathy.

Gastrointestinal tract: dysmotility, malabsorption, sometimes bleeding.

Soft tissues: macroglossia (enlarged tongue, a relatively specific sign), periorbital purpura, soft tissue infiltration.

Why early diagnosis matters. AL amyloidosis is often diagnosed late because early symptoms (fatigue, swelling, mild proteinuria) overlap with many other conditions. Late diagnosis with advanced cardiac involvement substantially worsens outlook because the damage to the heart accumulates while plasma cells continue producing more amyloid. Modern guidelines emphasise structured workup of unexplained heart failure with preserved ejection fraction, unexplained proteinuria, and the constellation of features that should raise AL amyloidosis suspicion.

The diagnostic workup.

Monoclonal protein testing: serum free light chain ratio, serum and urine immunofixation, often bone marrow biopsy to assess the underlying plasma cell clone.

Amyloid identification: tissue biopsy (often of fat pad, kidney, or heart) with Congo red staining showing characteristic apple-green birefringence under polarised light. Immunohistochemistry or mass spectrometry to type the amyloid (AL versus ATTR versus other types is critical because therapy is different).

Organ involvement assessment: echocardiography with strain imaging, cardiac MRI, NT-proBNP and troponin (used as both diagnostic clues and prognostic markers), kidney function testing, neurological assessment.

The therapy approach.

Daratumumab plus VCd (cyclophosphamide-bortezomib-dexamethasone): now first-line standard for most patients. The ANDROMEDA trial established this combination as substantially superior to VCd alone, and it is now the modern reference regimen.

Autologous stem cell transplant: an option for selected fit patients with limited cardiac involvement, sometimes used after initial induction therapy.

Maintenance therapy: lower-intensity treatment to maintain hematological response, with options varying by patient.

Second-line and beyond: alternative combinations, isatuximab-based regimens (in late-stage data), other plasma cell-directed therapy.

Emerging tier: anti-amyloid antibody programs (birtamimab targeting deposited amyloid for clearance, others) are in late-stage trials with the proposition of accelerating organ recovery by removing existing amyloid deposits in addition to plasma-cell-directed therapy that stops new amyloid production.

Supportive care: heart failure management, anticoagulation when indicated, renal support, nutritional support, and management of other organ-specific issues.

What to expect. AL amyloidosis outcomes have improved substantially in the past decade with the modern combination therapy. Earlier diagnosis (so therapy can start before extensive cardiac damage) is the most important thing; structured awareness in heart failure clinics, nephrology, and primary care has grown but continues to expand. Care at a centre with amyloidosis expertise is the standard, and multidisciplinary management addresses the multiple organ dimensions of the disease.