Cancer of Unknown Primary With Squamous Cell Carcinoma Phenotype Presenting as Isolated Axillary Mass

Cancer of unknown primary (CUP) is a rare metastatic malignancy where no primary tumor can be found. We report the case of a 71-year-old female with a strong family history of breast cancer presenting with isolated axillary lymphadenopathy after a tick bite. A biopsy of the axillary mass revealed poorly differentiated squamous cell carcinoma and after extensive evaluation, she was diagnosed with metastatic squamous cell carcinoma with unknown primary tumor. We present this case because of the role of confounding history complicating her initial diagnosis and bringing awareness to a rare disease.