Diffuse normolipaemic plane xanthomatosis. An abnormal complement component profile.

A patient with diffuse normolipaemic plane xanthomatosis, a benign monoclonal gammopathy, and a low total serum complement level is described. Functional haemolytic assays revealed decreased levels of C1, C4 and C2 components and elevated levels of the two terminal components C8 and C9. Radial immunodiffusion demonstrated low levels of C1q and C4 and a high level of C3. Both functional and immunochemical studies revealed extremely low levels of the inhibitor of C1 esterase. Anticomplementary activity was not present in the patient's serum. Despite low concentrations of the early reacting components of the classic complement pathway, the alternate pathway seemed to be intact. It was concluded that the patient had the recently delineated syndrome of acquired deficiency of the C1-esterase inhibitor.