Abstract

Cytokeratins are a family of polypeptides of intermediate filaments which in diverse epithelia are expressed in diffeent, yet specific combinations. To evaluate the diagnostic value of keratin, immunohistochemical staining was done in formalin-fixed, paraffin-embedded normal and neoplastic tissues by PAP and StreptABC methods. The antiserum for cytokeratin in monoclonal antibody which gives the specificity for 40, 46, 50, 52, 56, 58, and 65-67 Kd keratin classes. The results are as follows: 1) The staining was positive for cytokeratin in all of the squamous epithelium, ductular epithelial cells of various glands, respiratory and urinary tract epithelium, and mesothelial cells. 2) No staining for cytokeratin was ovserved in respiratory alveolar epithelium, acinar cells of various glands, renal glomeruli, hepatocytes, and many mesoderm-derived tissues such as muscle, hematopoieitc and lymphoid tissues, nerve, bone, cartilage, and fibroblasts. 3) Squamous cell carcinomas, transitional cell carcinomas, mesotheliomas, and some of the adenocarcinomas (stomach, colon, uterine cervix, biliary tract and breast) exhibited positive staining for cytokeratin. Epithelial cells of thymoma, adenomatoid tumor, plemorphic adenoma of salivary gland, papillary carcinoma of thyroid, lymphoepithelioma, and craniopharyngioma were also positive. 4) Some of the adenocarcinomas (prostate and pancreas), renal cell carcinoma, ovarian stromal and germ cell tumors, hepatocellular carcinoma, malignant melanoma, and mesoderm-derived tumors including malignant lymphoma were uniformly negative for staining. 5) From the above results, the immunohistochemical study in paraffin-embedded tissues using monoclonal antibody for cyto keratin may be useful to differentiate various tumors, especially in differential of hepatocellular carcinoma from bile duct adenocarcinoma, lymphoepithelioma and other undifferentiated carcinomas from lymphoma, thymoma from lymphoma, and squamous cell carcinoma from melanoma. It will be helpful in the diagnosis of transitional cell carcinoma in which the differentiation from renal cell carcinoma and prostatic adenocarcinoma be difficult.

• Keywords: Cytokeratin;tumor;