Crospovidone, another pharmaceutical tablet filler material that was also seen in the lungs of subjects 1 through 3, had an irregular, corallike shape; was nonbirefringent; and stained yellow-green to blue-green with MMPS (Figure 11).
In comparison to the results obtained with MMPS, GMS stained cellulose fibers gray to black whereas Congo red imparted an orange color to MCC.
Traditionally, MMPS has been used in pulmonary or cardiovascular pathology to assess vascular remodeling.
The saffron component of MMPS also stains cellulose yellow, whereas the alcian blue component of the MMPS tends to tint talc particles (and probably other silicates) light blue.
It is our assumption that the blue coloration of talc in the MMPS does not represent a true chemical staining reaction with the mineral particle, but likely, represents staining of mucopolysaccharides coating the outer surface of the particle in tissue, or perhaps nonspecific electrochemical bonding between stain and mineral particle.
3) The MMPS also serves to discriminate crospovidone (polyvinyl-Npyrrolidone) from MCC, although this distinction is usually not as crucial because the identification of crospovidone can be readily made based on the corallike shape of the particle, its lack of birefringence, and its deep basophilia with hematoxylin-eosin stain.
7,13) The dual value of the MMPS is that it not only helps to identify MCC but also serves to localize the material within either the bronchiolar or the vascular compartment through its elastic staining properties, and thereby suggests the pathway by which the MCC gained access to the lung.
As suggested by our study, MMPS may be useful in identifying other crystalline materials in tissue.
The MMPS may also prove to be useful in evaluating crystalline deposits in cases of alleged intravascular crystalline precipitation of hyperalimentation fluid.
Despite its usefulness, the MMPS is a technically challenging stain to perform.