Natural history and outcomes in localised immunoglobulin light-chain amyloidosis: a long-term observational study

Background Localised immunoglobulin light-chain amyloidosis, involving one type of tissue, is rare. Little systematic data exists regarding clinical presentations, course or outcomes, or risk of progression to systemic amyloidosis. We aimed to report clinical features and outcomes of a large series of patients with localised light-chain amyloidosis. Methods We examined data for all patients with localised amyloidosis who were diagnosed, assessed, and followed at the UK National Amyloidosis Centre (NAC) between Jan 2, 1980, and Dec 15, 2011, from the NAC database and written records. The inclusion criteria was the presence of biopsy sample proven localised amyloidosis classified as biopsy proven amyloid deposition confined to one site or tissue proven by histology of the tissue examined), without any evidence of vital organ involvement, which was defined as cardiac, renal, or liver involvement or peripheral or autonomic neuropathy and treatment naive. Findings We identified 606 patients with biopsy proven localised amyloidosis (likely light-chain type in 98%) from 5050 newly diagnosed patients with all types of amyloidosis. Median age was 59.5 years (IQR 50.2-74.5). The most common sites included bladder (95; 16%), laryngeal or tonsillar (92; 15%), cutaneous (84; 14%), and pulmonary nodular (47; 8%). 121 (20%) had a monoclonal immunoglobulin or abnormal circulating free light chains. At median follow-up of 74.4 months (IQR 37.2-132.0), seven (1%) patients progressed to systemic immunoglobin light-chain amyloidosis. 270 (51%) patients had one repeated treatment intervention and 112 (21%) had more than one repeated treatment interventions (predominantly localised debulking). The estimated 5-year overall survival was 90.6% (95% CI 87.7-92.9) and 10-year overall survival was 80.3% (75.1-84.1). In patients aged 70 years or older, median overall survival was 12.1 years (95% CI 10.5-13.7). Interpretation Localised immunoglobulin light-chain amyloidosis has an excellent prognosis with no apparent effect on life expectancy. Evolution into systemic immunoglobulin light chain amyloidosis is very rare.