Secondary tumours

Definition

Tumours that metastasize to the nasopharynx from other primary malignancies. Direct invasion from tumours of adjacent sites, leukemias and lymphomas are excluded.

Epidemiology

Metastases to the nasopharynx are extremely rare {1685}. The majority of patients are over the age of 50 years. Reported primary tumours and tumour sites include malignant melanoma (cutaneous) 9 cases, kidney (3 renal cell, 1 Wilms), lung (4 cases), and one case each of breast, colon and cervical cancer {1685}.

Clinical features

Patients usually present with non-specific symptoms, such as headache, nasal obstruction, and symptoms related to cranial nerve involvement. Rarely, they present with nasal polyps {325}. Imaging studies show lytic destruction of the basisphenoid centred in the clivus. The tumour frequently extends into the middle cranial fossa and nasopharynx. Calcification is occasionally seen.

Histopathology

Chordomas typically show a lobulated growth pattern. Polygonal or ovoid tumour cells are arranged in cords, lobules and sheets in a myxoid background. The nuclei are typically round and uniform, but may exhibit considerable pleo-morphism. The cytoplasm is abundant and eosinophilic, and at times clear. Vacuolated cells (physaliferous cells) are present to a variable degree. The tumour cells are immunoreactive for cytoker-atins, epithelial membrane antigen and S100 protein.

The main differential diagnoses are epithelial neoplasms (such as mucinous carcinoma, salivary gland tumours, poorly differentiated carcinoma) and chon-drosarcoma. The lobulation, physalifer-ous cells and diffuse strong S100 protein immunoreactivity distinguish chordoma from carcinoma. Chondrosarcoma is negative for cytokeratin.

Prognosis and predictive factors

Chordoma is a low-grade tumour and distant metastases are rare. Chordomas involving the nasopharynx are often treated by radiation therapy because complete surgical resection is practically impossible because of the anatomy {709}.

Clinical features

Patients may be asymptomatic or present with nasal obstruction, epistaxis, unilateral serous otitis media secondary to blockage of the eustachian tube, or otalgia. Large bulky metastases can extend into the nasal cavity or deform the soft palate.

A long disease-free interval between treatment of the primary tumour and the appearance of metastasis in the nasopharynx may confuse the diagnosis, raising the possibility of a new primary neoplasm of the nasopharynx. However, this is not uncommon for malignant melanoma and renal cell carcinoma.

Pathogenesis

Most metastases to the nasopharynx are haematogenous, possibly arising in some instances through Batson's par-avertebral venous plexus.

Prognosis and predictive factors

Metastasis is an ominous sign associated with a poor prognosis.

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