Uncompacted myelin lamellae in two cases of peripheral neuropathy

Summary Peripheral nerve biopsies from two patients with chronic sensorimotor neuropathy were studied. The first case was a non-Hodgkin malignant lymphoma and did not show any dysglobulinemia. The second case had a benign monoclonal gammopathy IgG, Lambda type. Direct immunofluorescence showed no deposits in the first case and slight deposits of anti IgG sera on a few myelinated fibers in the second case. There were numerous fibers showing uncompacted myelin lamellae, 7% in the first case and 4% in the second case. Some of these fibers had axons containing more tubules than filaments. The very few cases reported on neuropathies showing that uncompacted myelin lamellae were frequently associated with dysglobulinemic neuropathy. However, this ultrastructural abnormality of the myelin sheath can be observed without any dysglobulinemia.