The term “cancer of unknown primary” refers to a condition in which a patient has metastatic malignancy without an identified primary source. The majority of patients have malignancy which appears to derive from epithelial cells and hence are regarded as having carcinoma of unknown primary. Cancer of unknown primary (CUP) is diagnosed following histological confirmation of malignancy with no obvious primary after a detailed history, examination and investigations. It occurs in 4–5% of patients presenting with invasive cancer .