How Is Carcinoma of Unknown Primary Classified?
If your doctor still cannot find the primary site of the cancer after doing a number of different tests, you may be officially diagnosed with carcinoma of unknown primary origin (CUP). A pathologist will review the biopsy samples and typically classify the cancer as one of these five most common types:
Squamous cell carcinoma
Poorly differentiated carcinoma
Poorly differentiated malignant neoplasm
The pathologist's classification of the cells from the biopsy will help your doctor to determine a treatment plan, even if the original site of the cancer remains unknown.
You may need some of these additional exams:
Underarm lymph node evaluation
Groin lymph node evaluation
Pelvic organ evaluation
Chest or abdomen evaluation
Evaluation of other locations
Test for melanoma of unknown primary origin in your neck, underarms, or groin lymph nodes
Doctors will repeat a careful physical exam and maybe some of the prior tests. They will have a second pathologist look at the biopsy samples. Sometimes, as time passes, a small hidden primary tumor may become large enough to be found. This may help the doctors reclassify the CUP.