About 3% of all patients with cancer have cancer of unknown primary origin (CUP). This study is on a patient who reported for a gynecologic checkup as she was on tamoxifen and noted to have metastatic lesions at multiple sites including pelvis, uterus, tubes, and ovaries. The case presented is interesting as the patient has no primary site of carcinoma of breast, but PET–CT scans and advanced immunohistochemistry techniques used for the metastatic tissue showed strong positivity to breast carcinoma. Various intensive tests were needed to diagnose the primary site without a lesion. Also, the patient received the first-line chemotherapy, multiple transfusions, debulking surgery, and then the second-line chemotherapy. With a poorly differentiated carcinoma spread all over the skeletal system, gut, abdomen, and pelvis, the patient tolerated the second-line chemotherapy also and is still surviving 2 years after the detection of CUP.
Carcinoma of unknown primary origin, positron emission tomography, 18 F-fluorodeoxyglucose, immunohistochemistry, debulking surgery