Oncocytic intraductal carcinoma (IDC) is a rare subtype of salivary IDC characterized by an oncocytic cell proliferation surrounded by a p63-positive myoepithelial rim. We presented a case of oncocytic IDC: a 70s-year-old male with a swelling in the right parotid gland. Fine-needle aspiration cytology revealed complex papillary cell clusters with an abundant granular cytoplasm and a small number of myoepithelial cells. The cytologic features corresponded to the histological features of oncocytic IDC. The oncocytic cells were positive for S-100, mammaglobin, anti-mitochondrial antibody, and BRAF V600E. Sanger sequencing further confirmed BRAF p.V600E variant. Because a definite preoperative cytological diagnosis of oncocytic IDC is challenging, ancillary tests using cell blocks can aid in the diagnosis.
Hirata et al. (Sun,) studied this question.