aCase 7a

by Dr.Chua

This 58-year-old Iban man received treatment (surgical excision followed by radiotherapy) for nasopharyngeal carcinoma one year ago. He presented recently with a swelling in his right lower lid and a vertical diplopia (Fig. 1). Examination revealed normal vision in both eyes. He had a right proptosis with hypertropia and restricted downgaze. A hard mass was palpable along the inferior orbital margin. He had no complaint of epiphora. A CT scan was performed which revealed a mass (Fig 2) in the orbital floor without bony destruction or cavernous sinus involvement. Biopsy of the lesion (Fig. 3)showed a white mass with firm consistency. The histology revealed a moderately differentiated squamous cell carcinoma consistent with the previous histology of his nasopharyngeal carcinoma. Endoscopic examination of the nasal cavity and the right maxillary antrum were unremarkable and the biopsy in these areas showed no malignancy. The orbital lesion was diagnosed as metastatic nasopharyngeal carcinoma and the patient underwent radiotherapy.

Figure 1. Right hypertropia and proptosis.

Figure 2. CT scans a diffuse mass involving the inferior orbit.

No bony destruction is seen.

Figure 3. Biopsy through a subciliary incision of the right lower lid

revealing a white firm mass in the orbital floor.

a. What is the geographical distribution of nasopharyngeal carcinoma (NPC)?

In Western Europe and North America NPC is rare and accounts for fewer than 1 % of all malignancies in adults. This cancer has an intermediate incidence of five to nine cases per 100,000 population per year in inhabitants of northern China, the Mediterranean basin, North Africa and Southeast Asia.This cancer has its highest incidence in southern China escpecially in Hong Kong and Guangzhou, with documented rates of 10 to 150 cases per 100,000 population per year. For this reason, this cancer is often referred to as "Cantonese cancer" or "Kwangtung tumor."¹

b. Is orbital metastasis a common way for nasopharyngeal carcinoma (NPC) to invade the orbit?

Although NPC commonly metastasizes to cervical lymph nodes, orbital metastasis are rare. Most cases of orbital involvement are through direct invasion typically via the cavernous sinus into the apex causing proptosis and muscle paralysis.² Less commonly, the direct spread may be via the nasolacrimal duct and in such cases epiphora is common.³

c. Is the histology seen in this patient typical of nasopharyngeal carcinoma (NPC) in this part of the world?

No. Most cases of NPC seen in Malaysia belong to WHO-3 ie. undifferentiated carcinoma.

The World Health Organization (WHO) has classified NPC into 3 categories:

• WHO-1 is defined as well–to–moderately differentiated squamous or transitional cell carcinoma with keratin production.

• WHO-2 is nonkeratinizing carcinoma.

• WHO-3 is undifferentiated carcinoma

d. What is the relationship between Epstein Barr virus antibodies and nasopharyngeal carcinoma (NPC)?

The relationship between NPC and Epstein-Barr virus was first observed in 1966, when the sera of patients with the cancer were found to show precipitating antibodies against cells infected with the virus.⁴ Later studies revealed elevated levels of IgG and IgA antibodies directed against components of Epstein-Barr virus in patients with NPC.⁵ The high antibody titres to EBV antigens in NPC patients can serve as a marker for the diagnosis of NPC especially if the patients have signs of NPC but no NPC is seen during endoscopic examination. However, elevated EBV titers may also be associated with other disease entities, such as sinonasal undifferentiated carcinoma (SNUC), sinonasal lymphoma, and tongue cancer.
　

e. What is the prognosis for this patient?

The life span is shortened in orbital metastases. However, palliative treatment in the form of radiotherapy or chemotherapy can be useful in preventing  troubling symptoms of pain and visual loss. Surgery is rarely curative but debulking can play a part in relieving symptoms if there were pain or visual loss. One study of NPC with orbital invasion showed a 5-year survival rate of 28% , indicating that it is associated with poor prognosis.
　

Reference:

1. Collins SL. Squamous cell carcinoma of the oral cavity and oropharynx. In: Ballenger JJ, Snow JB Jr., eds. Otorhinolaryngology: head and neck surgery. 15th ed. Media, Pa.: Williams & Wilkins, 1996:249-368.

2. Liaw CC, Ho YS, Ng KK. Nasopharyngeal carcinoma presenting as a retro-orbital mass - Report of three cases. Otolaryngol Head Neck Surg 1990; 103(5):825-8.

3. S Amrith. Antero-Medial Orbital Masses Associated with Nasopharyngeal Carcinoma Singapore Med J 2002 Vol 43(2) : 097-099

4. Old LJ, Boyse EA, Oettgen HF, dé-Harven E, Geering G, Williamson B, et al. Precipitating antibody in human serum to an antigen present in cultured Burkitt's lymphoma cells. Proc Natl Acad Sci U S A 1966;56:1699-704.
　

5. Vasef MA, Ferlito A, Weiss LM. Nasopharyngeal carcinoma, with emphasis on its relationship to Epstein-Barr virus. Ann Otol Rhinol Laryngol 1997;106:348-56.