Contralateral Cervicomediastinal Lymph Node Metastases from Clinically Occult Adenocarcinoma of the Lung

A 69-year-old woman with a right cervical lymphadenopathy presented with an adenocarcinoma on excisional biopsy. Computed tomography (CT) scans and a positron emission tomography scan demonstrated that the tumor was localized in the right paratracheal and cervical region. A clinical diagnosis of lung cancer arising from an unknown primary site was made based on the radiologic and immunohistochemical findings. Serial CT scans showed a growing nodule in the left apex from pinpoint size to 1 cm in diameter after several months, which was defined as the primary site at autopsy. The finding of a clinically occult lung cancer directly spreading to the contralateral mediastinal and cervical nodes by skipping ipsilateral hilar and mediastinal nodes is rare.