Update on Sinonasal Adenocarcinoma: Classification and Advances in Immunophenotype and Molecular Genetic Make-Up

Abstract

Adenocarcinomas of various types comprise 10% to 20% of all primary malignant neoplasms of the nasal cavity and paranasal sinuses [1]. Salivary Gland-Type Adenocarcinomas Adenocarcinomas of salivary-gland type are uncommon constituting 5–10% of sinonasal adenocarcinomas. They are thought to originate from seromucus glands of the nasal cavity and paranasal sinuses as well as the surface epithelium. Histologically, these carcinomas are similar to those originating from major and minor salivary glands [2]. The most common type is adenoid cystic carcinoma (Fig. 1) usually occurring in the maxillary sinus and nasal cavity [3]. Long-term prognosis is poor and patients usually die due to local spread with no metastasis. Adenocarcinoma Not Otherwise Specified may exhibit many high-grade, poorly differentiated growth patterns, and should be considered as a diagnostic entity for many high-grade salivary gland-type adenocarcinomas of the sinonasal tract. These tumors have a poor prognosis [1, 4]. Fig. 1 Adenoid cystic carcinoma of nasal cavity. Classic cribriform and cystic pattern with bland nuclear appearance. Nasal surface epithelium is at the top left corner. H-E-stain x250 Other types of salivary adenocarcinomas are rare in the sinonasal tract but cases of acinic cell carcinoma, mucoepidermoid carcinoma (Fig. 2) [5], epithelial-myoepithelial carcinoma, basal cell adenocarcinoma, salivary duct carcinoma, polymorphous low-grade adenocarcinoma (terminal tubulus adenocarcinoma) [6], and carcinoma-ex-pleomorphic adenoma have been reported. The possibility of specific types of salivary gland-type adenocarcinomas should be taken into account when considering the diagnosis of a sinonasal adenocarcinoma. Table 1 lists the occurrence of different types of salivary gland-type tumors in the sinonasal tract. Fig. 2 Low-grade mucoepidermoid carcinoma of nasal cavity. Islands of intermediate cells contain mucous cysts and few epidermoid cells. Nasal surface epithelium at left. H-E stain x250 Table 1 Occurrence of sinonasal tumors of salivary gland type (modified from reference #5) Non-Salivary Gland-Type Adenocarcinomas The WHO classification of non-salivary gland-type adenocarcinomas [7] follows a classical distinction into intestinal-type adenocarcinoma and non-intestinal-type adenocarcinoma. WHO further subdivides the latter into low-grade and high-grade carcinoma [7]. Another approach first pools the various types of non-salivary gland-type sinonasal adenocarcinomas together and distinguishes them into six histological groups: low-grade, papillary, colonic, solid, mucinous, and mixed types [8]. In this presentation, the WHO classification of 2005 is used.