The cytological demonstration of the peroxidase activity in smears from thyroid goiters

A new modification of the benzidine methods for demonstration of the peroxidase activity has been developed and applied to smears obtained from goiters by fine needle aspiration biopsy. Only this method could yield positive results in toxic goiters and warm nodules. In cold nodules the peroxidase activity could not be found. The possible sources of errors and the causes of negative results when employing conventional methods as well as the possible significance of the demonstration of theperoxidase activity for clinical cytology of goiter have been discussed.