An undifferentiated malignant tumor on immunohistochemical stain shows cytoplasmic positivity of most of the tumor cells for cytokeratin. The most probable diagnosis of the tumor is
Immunohistochemistry is used for making categorization of undifferentiated tumors. The important examples include: Cytokeratin (carcinoma), Desmin (Leiomyoma and Rhabdomyosarcoma) and vimentin (Sarcomas).
Carcinoma
Lymphoma
Sarcoma
Malignant melanoma