Cutaneous amyloidosis.

Amyloidosis is generally classified as either systemic or cutaneous, with both primary and secondary forms. There are also heredofamilial and hemodialysis-associated varieties of amyloidosis, all with specific amyloid fibril derivatives. Nodular cutaneous amyloidosis is the most rare form of primary cutaneous amyloidosis. Lesions typically present as a crusted nodule on the face, extremities, or acral sites. The amyloid fibrils are immunoglobulin-derived and either kappa or lambda light chains. Systemic involvement is dependent on plasma cell amyloid protein deposition. Lesions may otherwise be classified as a local plasma cell clone or cutaneous plasmacytoma. Recent reports state that there is <10% risk of systemic progression. Workup should include at least a full history and physical examination; serum protein electrophoresis and urine protein electrophoresis; and gingival, rectal, or abdominal fat pad biopsies to rule out the presence of extracutaneous amyloid deposition. Management of nodular cutaneous amyloidosis is challenging, as there is no consistently effective treatment and local recurrence is common.