K20/CK20 staining on inguinal lymph nodes

JKeyes

Hello

Does anyone know the reason why K20/CK20 staining would be done to a lymph node biopsy? I went into the Dr office to get my results and the nurse came in and told me that they were sent out for staining and would not be ready for another few days. It has already been a week. I just want to know if this type of staining is done when cancer is already determined by the biopsy, in order to figure out course of treatment, OR, if it is done to determine if cancer is present at all. Is this standard testing...or additional special testing? Thank you.