[The immunological cause of auricular pseudocyst]

To elucidate the relationship between the auricular pseudocyst and the systemic and local immunological status.

The cyst fluid and blood samples of 44 cases were collected to measure contents of IgG, IgA, IgM and complement C3 by radial immunodiffusion, the content of immune complex by polyethylene glycol turbidimetry, DNA of cytomegalovirus in the fluid by polymerose chain reaction, anti-nuclear antibody(ANA) by immunofluorescent technique and reactions between samples and frozen sections of healthy white rat.

Contents of IgG, IgA, IgM and C3 in the cyst fluid were significantly lower than those in the serum (P < 0.01). No immune complex could be detected in both serum and cyst fluid. No DNA of cytomegalovirus was found in cyst fluid, whereas ANA was discovered. Reactive immunocomplex in the auricular cartilaginous tissue was found in the frozen sections of white rats.

The results suggest that auriular pseudocyst may be an autoimmune disease involving the auricle. The possible mechanism may be an accumulation of reactive exudate due to immunoreactions of autologous antibody and auricular tissue.