Primary Systemic AL Amyloidosis

The true incidence of AL amyloidosis, an orphan disease, remains unknown. Extrapolating a 30-year experience at the Mayo Clinic, Gertz et al. (6) estimated that 3200 new cases occur annually in the United States. The National Center for Health reported an incidence of 4.5 cases per 100,000 population in the United States—or nearly 13,500 cases per year (7). Between 1994 and 2002, we evaluated 701 patients with AL amyloidosis at Boston University Medical Center (8). 

To define the contributions of lung and heart involvement on AL disease course. Smith et al. (14) reviewed autopsy findings in 26 AL patients at Johns Hopkins Hospital. Ninety-two percent had moderate-to-severe heart infiltration 

Hemoptysis, hemothorax, or alveolar hemorrhage may occur suddenly. In a case of massive hemoptysis, histologic examination of a resected lower lobe revealed dissection of a medium-sized pulmonary artery containing amyloid deposits (16). 

Among the 29 case reports over the past 30 years (17-19), 19 cases provide sufficient data to establish the diagnosis of AL amyloidosis. Pleural biopsies documented amyloid deposits in 13 (68%) of these cases. Although 16 of 19 cases (84%) had concomitant congestive heart failure (CHF), 56% expressed exudative pleural fluid chemistries, suggesting disruption of pleural membrane mechanics. 

The physiology of amyloid pleural effusions is complex. AL amyloidosis can alter the function of several organs that could contribute to effusion formation including the heart (infiltrative cardiomyopathy—48% cases), kidneys (nephrotic syndrome—65% cases), and thyroid (hypothyroidism—4% cases) (20). 

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