Neoplastic Conditions

Benign tumours: sinonasal papillomas are uncommon but are the most frequent benign neoplasms, subdivided into fungiform, inverted and cylindrical cell types. They occur twice as often in males as in females and affect adults aged between 30 and 60 years. They are usually unilateral lesions but may be multiple or multifocal. Inverted papillomas are the commonest form, found on the lateral nasal wall and sinuses. They have an endophytic growth pattern and are composed of thick non-keratinising "transitional" epithelium within oedematous stroma. Fungiform papillomas are exophytic lesions composed of transitional epithelium supported by fibrovascular stroma, found exclusively on the nasal septum. Cylindrical cell papillomas are rare. They are similar in distribution and appearance to inverted papillomas but are composed of tall columnar (cylindrical) oncocytic cells.

Other benign neoplasms include pleomorphic adenoma, solitary fibrous tumour, haeman-giopericytoma, nasopharyngeal (juvenile) angiofibroma, sinus osteoma, meningioma, teratoma and paraganglioma.

Sinonasal cancer: the maxillary sinus is the commonest site for sinonasal malignancy and is usually either squamous cell carcinoma or adenocarcinoma in type. The nasal cavity is the second commonest site and is affected by a broad spectrum of lesions but tumours of the sphenoidal and frontal sinuses are rare. Risk factors include tobacco use, exposure to hard and soft wood dusts, nickel and irradiation.

Squamous cell carcinoma: the vast majority of malignant tumours of the mucosal lining of the nasal cavities and sinuses are classified as squamous cell carcinoma. The maxillary or ethmoid sinuses are the commonest sites but the nasal vestibule or septum can be affected. Many tumours have a "transitional cell" pattern, similar to that seen in inverted papillomas but exhibiting pleo-morphism, necrosis and a broad, pushing invasive front. The term "non-keratinising squamous cell carcinoma" can be used but a spectrum of changes including the presence of single cell infiltration and/or abundant keratinisation may be seen, sometimes making distinction from the usual type of squamous cell carcinoma impossible.

Salivary gland-type adenocarcinoma: the second commonest type of malignant tumour with adenoid cystic carcinoma the pattern most often encountered.

Intestinal-type sinonasal adenocarcinoma: adenocarcinoma exhibiting the differentiation pattern of large or small intestinal mucosa, with or without cytological atypia. Strongly associated with hard wood dusts (males, ethmoidal sinuses) but may occur sporadically (females, maxillary sinus). Commonest pattern mimics colonic adenocarcinoma - metastasis needs to be excluded. Mucinous tumours with signet ring cells are rare.

Malignant lymphoma: all types of non-Hodgkin's lymphoma may affect the sinonasal region either as a site of origin or as part of disseminated disease; diffuse large B-cell lymphoma is the commonest. T-cell and natural killer cell lymphomas often demonstrate a striking tendency for vascular involvement, sometimes with bizarre acute ischaemic changes, such as tooth exfoliation and bone necrosis. The tumour cells may be small, large or intermediate in size; the admixture of other inflammatory cells masks the neoplastic component by mimicking an inflammatory condition such as infection or Wegener's granulomatosis.

Others: Low-grade sinonasal adenocarcinoma, olfactory neuroblastoma, malignant melanoma, small cell neuroendocrine carcinoma, sinonasal undifferentiated carcinoma, rhabdomyosarcoma, chondrosarcoma and chordoma are all uncommon.

Prognosis: outcome depends on the histological type of tumour as well as the extent of spread. Most lesions are advanced at presentation although lymph node metastasis with carcinomas is relatively infrequent. Local recurrence is a common problem in spite of radical surgery and radiotherapy. Melanomas, small cell neuroendocrine carcinomas and sinonasal undifferentiated carcinomas are particularly aggressive but five-year survival is the norm with adenoid cystic carcinomas. In certain subtypes, such as intestinal-type sinonasal adenocarcinoma and olfactory neuroblastoma, grading based on the degree of differentiation is important in that low-grade lesions do well while high-grade lesions do badly. Around 20% five-year survival is customary.

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