Ultrasound guided fine needle aspiration cytology diagnosis of collision tumor in a lymph node: Lymphoma and metastatic adenocarcinoma

Diagnosis of two distinct malignancies in a single sample is rare. Here we report a case of lung adenocarcinoma metastasized to a supraclavicular lymph node which was concomitantly diagnosed with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) using ultrasound-guided fine needle aspiration biopsy (US-FNA) sample. A 62-year-old Caucasian male presented with cough and bloody sputum. US-FNA of a supraclavicular lymph node showed two distinct cell populations and, based on morphological examination and immunohistochemical staining of the FNA cell block slides, diagnosed with CLL/SLL and metastatic lung adenocarcinoma. Flow cytometric analysis of peripheral blood supported the diagnosis of CLL/SLL. To our knowledge, this is a rarely reported cytology case in which metastatic lung adenocarcinoma is concurrently diagnosed with CLL/SLL in a single lymph node and can be diagnosed based an FNA sample.