The immunohistochemical staining of Alpha-1-Antitrypsin is considered to be very useful in the study of inherited AAT deficiency, benign and malignant hepatic tumors and yolk sac carcinomas. Positive staining for A-1-Antitrypsin may also be used in detection of benign and malignant lesions of an histiocytic nature. Sensitivity and specificity of the results have made this antibody a useful tool in the screening of patients with cryptogenic cirrhosis or other forms of liver disease with portal fibrosis of uncertain etiology.