Nodular pulmonary immunoglobulin light chain deposits with coexistent amyloid and nonamyloid features in an HIV-infected patient

Abstract

Isolated nodular pulmonary amyloidosis is a rare condition characterized by localized deposits of immunoglobulin (Ig) light chain amyloid. Nonamyloid nodular light chain deposits in lungs can occur in systemic light chain deposition disease. Both amyloid and nonamyloid light chain deposits have been described at separate sites in the same or different organs but rarely in lungs. We report the clinical, radiologic, and pathologic findings in a drug user infected with the human immunodeficiency virus who had multinodular pulmonary Ig light chain deposits consisting of both amyloid and nonamyloid granular morphologic features. The deposits, closely associated with numerous plasma cells, had a unique histochemical and ultrastructural profile, with intermixed Congo red-positive fibrillar amyloid and Congo red-negative granular nonamyloid components. Immunohistochemical and immunoelectron microscopic studies showed reactivity of both the fibrillar and granular deposits for kappa and lambda light chains but not heavy chains. There was no evidence of restricted clonality of local or bone marrow plasma cells, serum or urine monoclonal protein, or secondary causes of amyloidosis. The amyloid deposits (but not the nonamyloid deposits) were reactive with antibody to amyloid rho component. There was no staining for other types of amyloid, i.e., amyloid A or transthyretin. The relationship between pulmonary amyloidosis, infection with the human immunodeficiency virus, and illicit drug use is unknown. We conclude that the nodular pulmonary light chain deposits with both amyloid and nonamyloid morphologic features are related to local plasma cell proliferation and that the fibrillar and nonfibrillar components most likely result from different conformations of the Ig light chains.