Squamous Cell Carcinoma of Unknown Primary that Metastasized to an Inguinal Lymph Node: A Case Report

Carcinoma of unknown primary (CUP) is a malignant tumor with histological characteristics indicating metastasis in a patient with an unidentified primary lesion after whole-body evaluation at the time of examination. CUP incidence is similar in men and women, and average age at diagnosis is 60 years. Reports of overall incidence vary but CUP is believed to account for 1-5% of all cancers. We encountered a case of apparently metastatic squamous cell carcinoma of the inguinal region in a patient without a detectable primary lesion. We report this case and review the literature on CUP, to increase awareness of this rare lesion.