Systemic kappa light-chain deposition

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Abstract
The pathology of .kappa. light-chain deposition is described in a 55-yr-old man who presented with respiratory insufficiency and hepatomegaly. Biopsies of lung and liver showed PAS[periodic acid-Schiff]-positive deposits which did not stain with congo red, crystal violet or thioflavin-T. By indirect immunoperoxidase techniques, the deposits were composed of .kappa. light-chain Ig. EM revealed granular and fibrillar electron-dense material which lacked the characteristics of amyloid. Subsequent clinical studies showed this patient had a plasma cell dyscrasia. .kappa. light-chain deposition is not limited to the kidney. The first manifestation of a plasma cell dyscrasia may be systemic deposits of light chain. These deposits can be distinguished from amyloid by their immunochemical, tinctorial and ultrastructural appearance.