Immunohistochemical aspects of the link between Malassezia ovalis and seborrheic dermatitis

Aim An immunohistochemical study was undertaken to look at immune reaction to Malassezia ovalis in seborrheic dermatitis. Background The role of M. ovalis in seborrheic dermatitis remains a matter of controversy despite some therapeutic evidence with the use of antifungals, especially ketoconazole. Methods immunohistochemistry was performed on skin samples to evaluate the density of M. ovalis and to disclose deposits of immunoreactants at the level of the yeasts inside the stratum corneum. Results M. ovalis was always decorated with the antibody to Factor XIIIa. suggesting the presence of a transglutaminase in the yeast wall. Deposits of IgG and C3 were present underneath and in close apposition to collections of M. ovalis in seborrheic dermatitis, and absent in control materials, including various types of dermatitis. Conclusion The close topographical relationship between M. ovalis , IgG and C3 deposits is a new evidence suggesting a unique inflammatory reaction to the yeast in seborrheic dermatitis.