There are three distinct categories of sinonasal adenocarcinoma:
- Intestinal type adenocarcinoma
- Sinonasal type adenocarcinoma
- Salivary gland adenocarcinoma (usually malignant types eg: adenoid cystic carcinoma, mucoepidermoid carcinoma, acinar cell carcinoma)
Epidemiology
The exact incidence of the subtypes of adenocarcinoma is difficult to assertain.
Intestinal type sinonasal adenocarcinoma is far more frequent in men, likely due to an occupational aetiology. No such occupational association has been shown for the sinonasal non-intestinal type adenocarcinomas or salivary gland tumours.
Aetiology and Pathogenesis
There is a strong association between woodworking and the intestinal type adenocarcinoma. Other occupational factors may be important although the exact method of carcinogenesis has not been determined. Other adenocarcinomas have no known aetiology.
Natural History
Unlike most other sinonasal tumours, the intestinal type and non-intestinal type adenocarcinomas are more frequent in the ethmoid sinus than the maxillary sinus. The reason is not clear. Adenoid cystic carcinoma most frequently arises in the maxillary sinus and may spread locally or via perineural invasion.
Tumour/Normal Tissue Features
Intestinal Type Adenocarcinoma
There are several different patterns observed, which mirror adenocarcinomas arising from the large bowel. The most common form is colonic type, which contains glandular structures and minimal papillae. Papillary, mucinous and solid types may occur. Immunohistochemistry and electron microscopy show features similar to colonic adenocarcinoma.
Non-Intestinal Type Adenocarcinoma
These tumours are either low or high grade. Low grade tumours have an acinar glandular architecture with minimal stroma. High grade tumours have a solid growth pattern with minimal gland formation.
Salivary Gland Tumours
These tumours mirror those arising from other salivary gland sites. The most common variant in the sinonasal region is adenoid cystic carcinoma, which has a uniformly poor prognosis. These tumours generally demonstrate a cribriform/cystic archictecture and invade extensively through bone, accounting for poor prognosis. Mucoepidermoid carcinoma, although the most common in the salivary glands, is very rare in the sinonasal region.
