Metastasis in the subcarinal lymph node with unknown primary tumor

A 59-year-old man with previous anaplastic large cell T-cell lymphoma stage 3A was admitted with an isolated positron emission tomography(PET)-positive spot in a subcarinal lymph node. Diagnosis was achieved with endobronchial ultrasound-guided fine-needle aspiration demonstrating a well-differentiated squamous cell carcinoma but no primary tumor was visible on PET-computed tomography. Because of his previous lymphoma the patient was scheduled for mediastinoscopy where the diagnosis was confirmed. Subsequent gastroscopy was normal and a right-sided thoracotomy showed no evidence of cancer elsewhere, only an inoperable metastasis in a subcarinal lymph node which infiltrated the trachea, esophagus and aorta. Such isolated squamous cell carcinoma in a subcarinal lymph node without a primary tumor despite invasive work-up has not been reported before.