Lupus erythematosus cell preparation-antinuclear factor incongruity. A review of diagnostic tests for systemic lupus erythematosus.

The cases of 20 patients, each of whom has a positive lupus erythematosus cell preparation and a negative antinuclear factor test, are presented. The concept of a false-positive lupus erythematosus preparation is suggested. Five common mechanisms causing a false-negative antinuclear factor test are discussed and evaluated. Clinical material from the 20 patients is described and pitfalls in diagnosing systemic lupus erythematosus are reviewed.