Low-grade intraductal carcinoma of the salivary gland with prominent oncocytic change: a newly described variant.
AIMS
Low-grade intraductal carcinoma (LG-IDC) is a clinically indolent malignant tumour of the salivary glands. Because of its rarity, the histological variants of LG-IDC have not been well characterised. Herein, we describe five LG-IDC cases with prominent oncocytic change in the major salivary glands.


METHODS AND RESULTS
We examined five cases, three males and two females (mean age = 63 years), of LG-IDC with oncocytic change. The sites affected by LG-IDC were the parotid and submandibular glands. The lesions were macroscopically unilocular or multilocular cysts with a solid tumour arising from the cyst wall. Smaller tumour cell nests were also observed. As with classic LG-IDC, the cyst wall was surrounded by myoepithelial cells with no invasive component. The tumour cells had abundant oncocytic cytoplasm and proliferated in a low-papillary, tubular or cribriform pattern. Immunohistochemically, the tumour cells were diffusely positive for pan-cytokeratin, S100, mammaglobin and antimitochondria antibody, and were negative for androgen receptor and gross cystic disease fluid protein-15. Unlike classic LG-IDC, some of these cases demonstrated focal invagination of myoepithelial cells in the intraductal tumour.


CONCLUSION
Oncocytic LG-IDC should be recognised as a histologically unique variant of LG-IDC. Awareness of this entity is important to avoid erroneous diagnosis and inappropriate treatment for histological mimics.
['Nakaguro|Masato|M|http://orcid.org/0000-0001-6987-3043', 'Urano|Makoto|M|', 'Suzuki|Hiroaki|H|http://orcid.org/0000-0003-1889-4260', 'Yamada|Kazuyuki|K|', 'Sakaguchi|Asumi|A|', 'Ogura|Kanako|K|', 'Matsumoto|Toshiharu|T|', 'Ono|Noritsugu|N|', 'Asato|Tsuguharu|T|', 'Mikami|Yoshiki|Y|', 'Imai|Hiroshi|H|', 'Nagao|Toshitaka|T|']
D000368:Aged D044584:Carcinoma, Ductal D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D024862:Oxyphil Cells D012468:Salivary Gland Neoplasms
low-grade intraductal carcinoma oncocytic change myoepithelial cell invagination salivary gland tumour