We studied
cytokeratin (CK) expression immunohistochemically in 64
seminomas using a panel of commercially available antikeratin
antibodies and tested for association of CK expression with patient age,
tumor size, stage, and outcome. Seventeen
embryonal carcinomas were compared with
seminoma. CK7, CAM 5.2, AEI/AEIII, and wide-spectrum screening
keratin (WSK) were positive in 41%, 30%, 36%, and 36% of the
seminomas, respectively. CK20 and high-molecular-weight
keratin (
HMWK) were negative in all cases. CD30,
placental alkaline phosphatase (PLAP), and
epithelial membrane antigen (EMA) were positive in 6%, 100%, and 2% of cases, respectively. There were no differences in patient age, stage,
tumor size, or outcome between CK-positive and CK-negative
seminomas. CK7, CAM 5.2, AEI/AEIII, and WSK were positive in 100%, 88%, 94%, and 88% of
embryonal carcinomas, respectively. CK20 and
HMWK were negative in all cases. CD30, EMA, and PLAP were positive in 100%, 12%, and 76%, respectively. CKs are present in
seminoma, and their presence is not associated with a difference in patient age, stage, or outcome. In cases such as small needle biopsy specimens, CK and CD30 stains may be useful in separating
seminoma from
embryonal carcinoma.