The purpose of this study is to present an instance of pneumonia brought about by two different oils and to evaluate the simple histochemical method used for the differentiation of the two substances. Although there are many cases of oil pneumonia on record, there are only a few in which the identity of the particular oil involved was determined.
There are available several histochemical fat stains, among which are sudan IV, nile blue sulfate, osmic acid and the Ziehl-Neelsen stain. The use of these stains, singly or in combination, on both frozen and paraffin sections provides an unusually valuable tinctorial method of distinguishing between several oily substances. It must be remembered, however, that these methods cannot supplant the physicochemical analysis of oils extracted from the involved lungs. The latter method was first used by Fischer-Wasels,1 in 1933, and was extensively applied by Graef2 in 1939. Chemical methods of