Cytological features of metastatic ceruminous adenocarcinoma (not otherwise specified) in pleural effusion: A case report.

Ceruminous gland adenocarcinomas are uncommon malignant neoplasms arising from the ceruminal glands of the external ear canal. They include three variants: ceruminous adenocarcinoma (not otherwise specified, NOS), ceruminous adenoid cystic carcinoma, and ceruminous mucoepidermoid carcinoma. The clinicopathological details of these neoplasms have been described; however, due to their scarcity, their cytological features in humans have not been documented before. The objective of this study was to investigate the cytological, histological, and immunocytochemical features of a ceruminous gland adenocarcinoma with pleural effusion. We performed effusion cytology on a 57-year-old man who was diagnosed with ceruminous adenocarcinoma (NOS) 8 months earlier and found pleural metastases. The cytology revealed features similar to those seen via tissue pathology, such as irregular glandular architecture with dual cell populations and a solid pattern of tumour cells. Although ceruminous adenocarcinoma (NOS) is rare, recognising its cytology is important to eliminate it as a differential diagnosis.