Fine-needle aspiration diagnosis of metastatic intestinal-type sinonasal adenocarcinoma

Fine-needle aspiration biopsy is a reliable and accurate method for the diagnosis of nodal metastases of head and neck cancers. We report the cytopathologic findings of a case of metastatic sinonasal intestinal type adenocarcinoma (ITAC) in a 58-year-old man who presented with enlarged cervical lymph nodes on a follow-up imaging study, 5 months after resection of a sinonasal ITAC. Ultrasound-guided fine needle aspiration of the station 2B lymph node yielded moderately cellular smears with abundant background mucin pools, numerous naked, atypical nuclei, and rare cells with signet ring cell morphology. Rare mitoses, apoptotic bodies, and necrotic debris were also present. Occasional clusters of signet ring cells were also seen in the cell block sections. Immunoperoxidase stains showed these cells to be positive for CK20 and villin. The differential diagnosis included a metastatic signet ring cell adenocarcinoma from the gastrointestinal tract and a metastatic sinonasal ITAC. Review of the previously resected sinonasal ITAC revealed a similar morphology with signet ring cells and abundant extracellular mucin production; the immunostaining results were also similar to those obtained on previously resected sinonasal ITAC. This case emphasizes the importance of considering primary head and neck tumors with intestinal phenotype and immunophenotype in the differential diagnoses of cervical lymph node metastases with signet ring cell morphology.