Alpha-1-antitrypsin in a malignant mixed mesodermal tumor of the ovary.

A malignant mixed mesodermal tumor of the ovary was found to contain multitudinous clusters of eosinophilic hyaline globules in both its epithelial and mesenchymal components. These periodic acid-Schiff-positive, diastase-resistant globules revealed typical positive ring-like staining for alpha-1-antitrypsin (AAT) using an indirect immunoperoxidase technique. Similar findings have previously been reported in certain germ cell and liver tumors and hepatocytes of patients bearing the Z-allele for AAT. The globules also stained with antisera against kappa and lambda immunoglobulin light chains, indicating the presence of surface immunoglobulin. In the electron microscope, the inclusions appeared granular and may have been derived from flocculent material in the dilated rough endoplasmic reticulum. These observations suggest a structural change in the tumor AAT analogous to that proposed for hereditary AAT deficiency. As a histogenetic marker, the presence of AAT in both epithelial and stromal cells suggests their origin from a common precursor cell.U