A case of a sinonasal adenocarcinoma with metaplastic ossification.

Sinonasal adenocarcinomas are rare tumours, with three subtypes. They are mostly low-grade tumours, although they can also be aggressive. In this case report, we describe a 34-year-old patient with sinonasal adenocarcinomas. Within his nasal cavity was found an irregular mass. Given the intratumoral calcification and bone, the mass was thought to be a bone-producing tumour, such as an osteosarcoma. The pathological diagnosis was a sinonasal adenocarcinoma with extensive metaplastic bone. To the best of our knowledge, this is the first case of a sinonasal adenocarcinoma with metaplastic ossification.