Pathologic fracture of odontoid process secondary to amyloid deposition.

Immunocyte dyscrasias have increasingly been reported in patients with gammopathy-associated systemic amyloidosis. In "primary" amyloidosis, deposits occur in heart, smooth and skeletal muscle, bones and joints, skin, lungs and peripheral nerves. The formation of amyloid fibrils appears related to the lambda light chains in these monoclonal gammopathies. A 72-year-old white man is reported who developed massive deposits of amyloid in joints and bones, as well as other tissues. Twenty percent of his bone marrow population was comprised of plasma cells in various maturational stages, without forming solitary masses diagnostic of myeloma. Lambda light chains were the sole contributors to a selective increase in IgD, with a concomitant reduction of IgA, IgG, and IgM. The patient sustained a pathologic fracture through a deposit of amyloid in the odontoid. While he suffered severe posterior nuchal and occipital pain, no clinical features of compression myelopathy were evident. Postmortem examination revealed a minor degree of posterior column degeneration and an axonal reaction of anterior horn cells of the C-1 spinal cord segment. This case represents the second to be reported with amyloidosis of the vertebral column, pathologic fracture, and a spinal cord lesion.