|Year : 2018 | Volume
| Issue : 1 | Page : 24-29
Nasopharyngeal carcinoma at the Ahmadu Bello University Teaching Hospital, Zaria: A 22-year histopathological review (1992–2013)
Sannom Mildred Yates1, Yawale Iliyasu2, Saad Aliyu Ahmed2, Almustapha Aliyu Liman2
1 Department of Anatomic Pathology and Forensic Medicine, Barau Dikko Teaching Hospital, Kaduna State, Nigeria
2 Department of Pathology, Ahmadu Bello University Teaching Hospital, Kaduna State, Nigeria
|Date of Web Publication||10-Oct-2018|
Dr. Sannom Mildred Yates
Department of Anatomic Pathology and Forensic Medicine, Barau Dikko Teaching Hospital, Kaduna State
Source of Support: None, Conflict of Interest: None
Background: Nasopharyngeal carcinoma (NPC) is uncommon cancer with unique geographical variations and strong association with Epstein–Barr Virus. The increasing incidence of NPC in Nigeria in recent years has reinforced the need for more studies to be done. This study aims to determine the frequency, age, and sex distribution as well as the histopathological patterns of NPC seen over a period of 22 years, from 1992 to 2013. Materials and Method: It was a retrospective study of all NPCs diagnosed in the Department of Pathology, Ahmadu Bello University Teaching Hospital from January 1st 1992 to December 31st, 2013. The request forms, histopathology reports, slides, and paraffin-embedded tissue blocks of all histologically diagnosed NPCs within the study period were retrieved and examined. The age, sex and site/nature of the biopsy were extracted. Histopathological diagnosis was in accordance to the 2005 World Health Organization classification. Results: NPC showed a frequency of 0.3% (112 cases) with a significant rise in incidence in the last decade. There was a male preponderance with M: F of 3.5:1. The age range was 6–91 years, mode 40 years, mean age 42.4 years, and peak age of incidence 40–49 years (18.8%). Histologically, nonkeratinizing carcinoma (NKC) was the most common (94.6%) followed by keratinizing squamous cell carcinoma (KSCC, 4.5%) and a single case of basaloid squamous cell carcinomas (bscc, 0.9%). Undifferentiated subtypes made up 79.4% of NKC, 12.7% differentiated and 7.9% mixed. In addition, 44.4% were of Regaud type growth pattern, 34.9% Schmincke type, and 20.6% were mixed. The nasopharynx was the most common site of surgical biopsy (57.1%) followed by the nasal cavity (17.9%) and cervical lymph node (11.6%). Conclusions: NPC showed a recent increase in frequency, a male preponderance and a unimodal age pattern that peaked in the 5th decade with an overall mean age of 42.4 years. NKC over KSCC and a solitary case of BSCC was seen. A significant number of biopsies were from sites outside the nasopharynx, suggestive of advanced disease with poor prognosis.
Keywords: Basaloid squamous cell carcinomas, keratinizing squamous cell carcinoma, nasopharyngeal carcinoma, nonkeratinizing carcinoma
|How to cite this article:|
Yates SM, Iliyasu Y, Ahmed SA, Liman AA. Nasopharyngeal carcinoma at the Ahmadu Bello University Teaching Hospital, Zaria: A 22-year histopathological review (1992–2013). Arch Med Surg 2018;3:24-9
|How to cite this URL:|
Yates SM, Iliyasu Y, Ahmed SA, Liman AA. Nasopharyngeal carcinoma at the Ahmadu Bello University Teaching Hospital, Zaria: A 22-year histopathological review (1992–2013). Arch Med Surg [serial online] 2018 [cited 2018 Oct 19];3:24-9. Available from: http://www.archms.org/text.asp?2018/3/1/24/243034
| Introduction|| |
Nasopharyngeal carcinoma (NPC) is “a carcinoma arising in the nasopharyngeal mucosa that shows light microscopic or ultrastructural evidence of squamous differentiation.” It, therefore, excludes adenocarcinoma, salivary gland-type carcinoma, hematolymphoid tumors, soft tissue, and bone tumors.
Globally, NPC is a relatively rare cancer and constitutes 0.6% of all the global cancer burden, making it the 24th most frequently diagnosed cancer worldwide., NPC shows a distinct geographical and racial distribution with the highest incidence reported in Malaysia, Indonesia, Singapore, Southern China, Southeast Asia, North Africa, and Alaska.,,
In Africa, the highest incidence is found in Tunisia and Algeria. In Nigeria, there is no comprehensive data, but regional reports show that NPC is the most common head and neck malignancy in Jos, Maiduguri, Sokoto and Lagos and the second most common in Port Harcourt.
There is a progressive increase in risk with age in most populations, and the incidence tends to rise after 30 years, then peaks at 40–60 years and starts to decline after that., NPC is more common in men with an incidence 2–3 times higher than in women.,
The most recent and widely used classification is the World Health Organization (WHO) classification of head-and-neck tumors, (2005) which classifies NPC based on histologic criteria, into keratinizing squamous cell carcinoma (KSCC) (Class I), Nonkeratinizing carcinoma (NKC) (Class II), and basaloid squamous cell carcinoma (BSCC) (Class III).
Although NPC has a consistent global association with Ebstein–Barr Virus (EBV), it has been shown to have a multifactorial etiology with an interplay of EBV infection, human papilloma Virus infection, consumption of salted food, consumption of meat containing nitrosamine, prolonged exposure to domestic wood cooking, smoking, prolonged exposure to formaldehyde, and genetic predisposition., Its distinctive geographical distribution, as well as time trends and migrant studies, further point to its multifactorial etiology.,
The difficulty in visualizing the nasopharynx, the vague nonspecific early symptoms and its tendency for submucosal spread makes an early diagnosis of NPC prove difficult and explains why the most common clinical presentation is cervical lymphadenopathy.,
This study aims to assess and to provide the disease frequency ratio and histopathological patterns of NPC in this region.
| Materials and Methods|| |
This is a 22 years' retrospective study carried out on all cases of NPCs diagnosed in the Department of Pathology, Ahmadu Bello University Teaching Hospital (ABUTH) Shika-Zaria, from January 1st, 1992 to December 31st, 2013.
All cases of histologically diagnosed NPCs within the study were extracted from the surgical pathology records of the department. The request forms, histopathology reports, slides and paraffin-embedded tissue blocks (PETB) were traced, retrieved and examined. The age, sex, site or nature of the biopsy and histological diagnosis was extracted. The histopathological patterns were analyzed using the hematoxylin and Eosin-stained slides, and all the cases were classified according to the WHO classification of NPCs (2005).
In cases of missing, faded, or broken slides, new sections were made from stored PETB. Cases in which both the request forms and duplicate histology reports were missing and where both archival slides and tissue blocks were missing, badly damaged or had insufficient tissue were all excluded from the study. The data obtained was analyzed using Microsoft Excel.
| Results|| |
A total of 9166 cancers were seen during the study, 1257 of the cancers were from the head-and-neck region and 112 were histologically diagnosed as NPC. Therefore, NPC constituted 1.2% of all cancers and 8.9% of the head-and-neck cancers seen.
The number of cases of NPC in the first half of the study period from 1992 to 2003 were low, ranging from zero (1992, 1993, 2000, and 2002) to three (1994. The second half, 2004–2013, however, showed an initially gradual increase in number of cases seen from 2004 to 2007. Afterward, there was a remarkably sharp rise to 21 cases in 2008 which decreased to 9 in 2009 and fluctuated subsequently between 10 and 15 cases recorded from 2010 to 2013 [Figure 1].
|Figure 1: Graph showing yearly distribution of nasopharyngeal carcinoma during the study period|
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There were 87 males (77.7%) and 25 females (22.3%) with a male-to-female ratio of 3.5:1. The ages ranged from 6 to 91 years with an overall mean age of 42.4 years and mode of 40 years. The females had a mean age of 41.8 years (age range 16–91 years) while the mean age for males was 42.6 years (age range 6–83 years). The peak age of incidence was 40–49 years age group with 21 cases (18.8%) closely followed by 30–39 years age group with 20 cases (17.9%) then 20–29 years, 50–59 years, and 60–69 years which had 18 cases each (16.1%). The lowest incidence was seen in 0–9 years and 90–99 years age groups, both of which had one case each (0.9%) [Figure 2].
|Figure 2: Bar chart comparing the age and sex distribution of nasopharyngeal carcinoma|
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NKC was the most common histological type, constituting 106 (94.6%) of cases, while 5 (4.5%) cases were KSCC and a single case (0.9%) of was seen BSCC [Figure 3].
|Figure 3: Bar chart showing the histopathological subtypes distribution of nasopharyngeal carcinoma|
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There were 82 males (77.4%) and 24 females (22.6%) with NKC, with a male-to-female ratio of 3.4:1. KSCC had 4 males (80%) and 1 female (20%) with a male-to-female ratio of 4:1. While a single male case of BSCC was seen (100%) [Table 1].
|Table 1: The sex distribution of different histological types of nasopharyngeal carcinoma|
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Further subclassification of the NKC showed that 50 (79.4%) were undifferentiated, 8 (12.7%) were differentiated and 5 (7.9%) were a mixture of both (Mixed) [Figure 4]. In addition, 28 (44.4%) were of the Regaud type growth pattern, 22 (34.9%) were of the Schmincke type, and 13 (20.6%) were a mixture of both (mixed) [Figure 5].
|Figure 5: Pie chart showing patterns of growth of nonkeratinizing carcinoma|
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The nasopharynx was the most common site of surgical biopsy with 64 cases (57.1%) followed by the nasal cavity, cervical lymph node and oropharynx with 20 (17.9%), 13 (11.6%) and 6 (5.4%), cases respectively. Ethmoidal and laryngeal masses were the least common with one specimen each (0.9%), while the rather vague neck mass made up 4 cases (3.4%). The exact site or nature of 3 (2.7%) of the specimens was not stated [Figure 6].
[Figure 7], [Figure 8], [Figure 9], [Figure 10] show representative photomicrographs of the histological types seen.
|Figure 7: Photomicrograph of undifferentiated nonkeratinizing carcinoma, schmincke type (H and E ×400)|
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|Figure 8: Photomicrograph of undifferentiated nonkerattinizing carcinoma, Regaud type (H and E ×400)|
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|Figure 9: Photomicrograph of differentiated nonkeratinizing carcinoma (H and E ×100)|
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|Figure 10: Photomicrograph of keratinizing squamous cell carcinoma (H and E ×400)|
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| Discussion|| |
NPC is uncommon worldwide except in areas of its endemicity., Accordingly, it accounts for 1.2% of all cancers seen at the Department of Pathology ABUTH, Shika-Zaria during the period of this study. This study population is considered to be in a low-risk region; however, some reports from different parts of Nigeria have shown that NPC is not so uncommon in our environment.,,,,,,,,,,,, Compared to the global report of NPC accounting for 0.6% of all cancers, it accounted for 2% of all cancers reported in Ibadan and Ilorin,, and 1.7% reported in Plateau.
An approximately 8-fold increase in frequency of NPC is observed in the second half of this study period compared to the first. Similarly, a sustained increase in incidence was observed by Nwaorgu and Ogunbiyi, who studied the trend of NPC in Ibadan over two decades (1981–2000). Otoh et al. also observed a rise in the occurrence of NPC when comparing the period's pre- and post-advent of HIV/AIDS in Nigeria in 1986. The reason for this recent increase is not well known but may probably be due to an increase in public health awareness, improved diagnostic techniques, HIV/AIDS pandemic, or environmental, dietary, and lifestyle changes. On the other hand, a steady decline in the incidence of NPC has been observed in Hong Kong since the 1970s, in Taiwan since the 1980s, and in Singapore Chinese since the late 1990s. A trend that could be attributable to the onset of rapid economic developments and consequent change in lifestyle and environmental risk factors in these places.,
This study showed a male preponderance with a male-to-female ratio of 3.5:1, consistent with reports in the literature of 2–3:1, irrespective of the incidence rate or geographical location., It is slightly higher than most local reports which hover around 2:1.,,,,
The mean age in this study is 42.4 years with an age range of 6–91 years. This compares favorably with reports from different parts of Nigeria where the mean age ranges from 41.1 to 44.4 years., A slightly higher mean age of 48.7 years has been reported from Ilorin. On the other hand, the mean age of incidence is about a decade higher in patients from North America, Western Europe, and China. The reason for this difference is unclear, but may not be unconnected with the lower life expectancy reported in Nigeria compared to these countries. The mean age for females is 41.8 years (age range 16–91 years) and 42.6 years (age range 6–83 years) for males. As observed in the literature, the age distribution is similar in males and females.
The peak age of incidence in this study is 40–49 years (5th decade) and the modal age is 40 years. Comparable findings have been reported in Maiduguri and Jos,, while a peak age of incidence in the fourth decade was seen in Ife, Sokoto and Ilorin.,,,, This unimodal age pattern is in contrast to the uniformly bimodal age distribution reported in low-risk populations, irrespective of sex and geographical location. In Nigeria, such bimodalities have been observed in studies done in Ibadan and Lagos., Kitcher et al. have also observed a bimodal age distribution in Ghana. On the contrary, recent comprehensive reviews have reported that NPC incidence increases monotonically with age in most of low-risk populations. This is more in keeping with the findings of this study and most other Nigerian studies which do not demonstrate bimodality.
Despite the relatively low frequency of NPC in this study, most patients were between 20 and 69 years which are their years of productivity with far-reaching implications regarding their socioeconomic output. The least age at presentation in this study is 6 years which is similar to what was seen in Maiduguri and Ibadan,, whereas higher figures were seen in Sokoto and Ilorin., In Ghana, Kitcher et al. observed a predominantly young age at presentation where 60.4% of the study population fell below 40 years, and the peak age of incidence was 10–19 years. Some studies in Tunisia, Kenya, Uganda, and Sudan (intermediate risk region) also showed that NPC was commonly seen in children and adolescents (0–19 year), though the reason for this remains unclear. This differs with the findings of this study where 9% are between 0 and 19 years of age.
NKC is the most common histological type seen in this study (94.6%). This is in consonance with reports from across Nigeria and worldwide, irrespective of age, sex, or geographical location.,,,,,,,, The proportion of NKC tends to differ, however, in different populations with recorded incidences of 95% and 75% in high- and low-risk areas respectively. The high frequency was seen in this study, 94.6%, is paradoxically closer to that of high-risk areas rather than low-risk areas as expected.
Further sub-classification of NKC showed that the undifferentiated subtype (formerly WHO Type III) predominates (79.4%) over the Differentiated subtype (formerly WHO Type II), with a small proportion having a combination of both subtypes. This is in agreement with existing literature.,,,,,,,, However, subclassification into the differentiated and undifferentiated subtypes has no clinical or prognostic significance. The predominant growth pattern observed in this study was the Regaud type constituting 44.4%, while Schmincke type made up 34.9%, the rest was a combination of both. These findings are considerably different from those of Nwaorgu et al., who reported a predominance of Schmincke type (56.1%) over Regaud (38.6%).
KSCC is the second most common (4.5%) histological type seen, which is in consonance with what has been reported globally., However, a conflicting report by Chang and Adami presented KSCCas the predominant histological type in low-risk areas. The incidence tends to vary considerably in different regions being relatively rare in high-risk areas (<2%), intermediate in intermediate risk areas (5%–10%) and highest in low-risk areas (25%). KSCC shows an unexpectedly low value (4.5%) for a low-risk area, such values would be expected in intermediate-risk areas. Similarly, low values have been reported in Ghana (5.8%) and Portugal (6.3%), both of which are low-risk areas as well. The report of 20% in Ilorin is more in keeping with the expectedly high frequency of KSCC in low-risk areas. Furthermore, a study in Sudan, an intermediate risk area, reported no KSCC. A single case of BSCC was seen (0.9%), which attests to the rarity already documented in literature.
NPC is notoriously malignant with extensive locoregional infiltration, early lymphatic spread and high rate of hematogenous spread to the bone, lung, liver, and distant nodes. This is compounded by difficulty in accessing the nasopharynx and vague symptoms, consequently, most patients present in advanced stages: 50%–65% presenting with locally advanced disease and 5%–8% with disseminated disease.,, Although most specimens in this study were from the nasopharynx (57.1%), presumably suggesting that they may be limited to the nasopharynx, the rest of the specimens (42.9%) are outside the nasopharynx, thus, suggesting advanced disease.
Cervical lymph nodes make up only 11.6% of the specimens seen in this study, a rather low figure when compared to the existing literature which report cervical lymph node enlargement as the commonest presenting symptom accounting for 72.5%–96.7% of cases.,,,,, However, this may not be a true reflection of the patients' clinical presentation as this study was not an extensive clinicopathological survey but rather a histopathological study and the site of biopsy does not exclude cervical lymph node enlargement. The high frequency of advanced disease may be attributed to late presentation.
| Conclusions|| |
In conclusion, this study has demonstrated a low frequency of NPC which has increased in the last decade, a male preponderance, a mean age of 42.4 years, a peak age of incidence in the 5th decade and a unimodal age pattern. It has also demonstrated the predominance of NKC over KSCC and the rarity of BSCC in our environment. The site/nature of the specimens shows that a number of them were taken outside the nasopharynx, suggestive of advanced disease with poor prognosis. The findings in this study, therefore, show several similarities and some peculiarities in comparison with those of other studies done in different parts of the country, Africa and globally.
Search of literature reveals an inadequate number of local studies done on NPC. More local studies including multicenter surveys and most pertinently population-based studies are needed. These studies should also be done periodically to document any changes that may be observed.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
Barnes L. World Health Organization, International Agency for Research on Cancer Pathology and Genetics of Head and Neck Tumours. Vol. 17. Lyon: IARC Press; 2005. p. 81-97.
Ferlay J, Soerjomataram I, Ervik M, Dikshit R, Eser S, Mathers C, et al
. Globocan 2012: Cancer Incidence and Mortality Worldwide v1.0. Lyon, France: IARC Cancer Base No. 11; 2013. Available from: http://www.globocan.iarc.fr
. [Last accessed on 2015 Mar 25].
Torre LA, Bray F, Siegel RL, Ferlay J, Lortet-Tieulent J, Jemal A, et al.
Global cancer statistics, 2012. CA Cancer J Clin 2015;65:87-108.
Parkin DM, Whelan SL, Ferlay J, Teppo L, Thomas DB. Cancer Incidence in Five Continents (Electronic Version). Vol. 10. Lyon: International Agency for Research on Cancer. Available from: http://www.ci5.iarc.fr
. [Last accessed on 2015 Mar 25].
da Lilly-Tariah OB, Somefun AO. Malignant tumours of the nasopharynx at jos university teaching hospital, Nigeria. Niger Postgrad Med J 2003;10:99-102.
Ahmad BM, Pindiga UH. Malignant neoplasms of the ear, nose and throat in North Eastern Nigeria. Highland Med Res J 2004;2:45-8.
Iseh KR, Malami SA. Pattern of head and neck cancers in Sokoto- Nigeria. Niger J Otolaryngol 2006;3:77-83.
Nwawolo CC, Ajekigbe AT, Oyeneyin JO, Nwankwo KC, Okeowo PA. Pattern of head and neck cancers among nigerians in lagos. West Afr J Med 2001;20:111-6.
Onotai L, Nwogbo A. Primary head and neck malignant tumours in Port Harcourt, Nigeria: A revisit. J Med Med Sci 2012;3:122-5.
Chang ET, Adami HO. The enigmatic epidemiology of nasopharyngeal carcinoma. Cancer Epidemiol Biomarkers Prev 2006;15:1765-77.
Bernard W, Stewart PK. World Cancer Report. International Agency for Research on Cancer IARC Press: Lyon; 2003.
Kitcher E, Yarney J, Gyasi R, Cheyuo C. Nasopharyngeal cancer: A review of cases at the Korle-Bu Teaching Hospital. Ghana Med J 2004;38:104-8.
Nwaorgu OG, Ogunbiyi JO. Nasopharyngeal cancer at the university college hospital Ibadan cancer registry: An update. West Afr J Med 2004;23:135-8.
Ologe FE, Adeniji KA, Segun-Busari S. Clinicopathological study of head and neck cancers in Ilorin, Nigeria. Trop Doct 2005;35:2-4.
Iseh KR, Abdullahi A, Malami SA. Clinical and histological characteristics of nasopharyngeal cancer in Sokoto, North-Western, Nigeria. West Afr J Med 2009;28:151-5.
Mandong B, Ngbea J, Adoga A. Head/Neck squamous cell carcinoma: Prevention strategy. Jos J Med 2011;5:12-6.
Adeyemi BF, Adekunle LV, Kolude BM, Akang EE, Lawoyin JO. Head and neck cancer – A clinicopathological study in a tertiary care center. J Natl Med Assoc 2008;100:690-7.
Garandawa HI, Ahmad BM, Nggada HA. Nasopharyngeal cancer in North – Eastern Nigeria: Clinical trends. Niger J Clin Pract 2009;12:379-82.
Alabi BS, Badmos KB, Afolabi OA, Buhari MO, Segun-Busari S. Clinico-pathological pattern of nasopharyngeal carcinoma in Ilorin, Nigeria. Niger J Clin Pract 2010;13:445-8.
] [Full text]
Amusa YB, Olabanji JK, Akinpelu VO, Olateju SO, Agbakwuru EA, Ndukwe N, et al.
Pattern of head and neck malignant tumours in a Nigerian teaching hospital – a ten year review. West Afr J Med 2004;23:280-5.
Obafunwa JO, Bhatia PL. Nasopharyngeal carcinoma in Plateau state, Nigeria: A pathological study. Eur J Surg Oncol 1991;17:335-7.
Otoh EC, Johnson NW, Ajike SO, Mohammed A, Danfillo IS, Jallo PH, et al.
Primary head and neck cancers in North -Western Nigeria. West Afr J Med 2009;28:227-33.
Luo J, Chia KS, Chia SE, Reilly M, Tan CS, Ye W, et al.
Secular trends of nasopharyngeal carcinoma incidence in Singapore, Hong Kong and los Angeles Chinese populations, 1973-1997. Eur J Epidemiol 2007;22:513-21.
Paul O. World Health Organization Report: Nigeria, Angola, Others' Life Expectancy Stagnant; 18 May 2014.
Fatusi O, Akinpelu O, Amusa Y. Challenges of managing nasopharyngeal carcinoma in a developing country. J Natl Med Assoc 2006;98:758-64.
da Lilly-Tariah OB, Somefun AO, Adeyemo WL. Current evidence on the burden of head and neck cancers in Nigeria. Head Neck Oncol 2009;1:14.
Bray F, Haugen M, Moger TA, Tretli S, Aalen OO, Grotmol T, et al.
Age-incidence curves of nasopharyngeal carcinoma worldwide: Bimodality in low-risk populations and aetiologic implications. Cancer Epidemiol Biomarkers Prev 2008;17:2356-65.
Ketiku KK, Igbinoba F, Okeowo PA. Nasopharyngeal cancer in Nigeria – A revisit. Niger Postgrad Med J 1998;5:7-12.
Skirbekk V. Vienna Yearbook of Population Research; Age and individual Productivity: A Literature Survey. Vienna: Austrian Academy of Sciences; 2003. p. 133-53.
Ellouz R, Cammoun M, Attia RB, Bahi J. Nasopharyngeal carcinoma in children and adolescents in Tunisia: Clinical aspects and the paraneoplastic syndrome. IARC Sci Publ 1978;20:115-29.
Gacani W, Bal IS, Babu MA, Oburra HO. Distant metastases from nasopharyngeal carcinoma at Kenyatta national hospital, Nairobi. East Afr Med J 2001;78:678-81.
Wei KR, Xu Y, Liu J, Zhang WJ, Liang ZH. Histopathological classification of nasopharyngeal carcinoma. Asian Pac J Cancer Prev 2011;12:1141-7.
Breda E, Catarino R, Azevedo I, Fernandes T, Barreira da Costa C, Medeiros R, et al.
Characterization of the clinical evolution of nasopharyngeal carcinoma in portuguese population. Acta Otorrinolaringol Esp 2007;58:191-7.
Abuidris DO, Elgaili EM, Elhaj AH, Elmustafa OM. Histopathological patterns of nasopharyngeal carcinoma in Sudan. Saudi Med J 2008;29:962-5.
Juan R. Nasal cavity, paranasal sinuses and nasopharynx. In: Juan R, editor. Rosai Ackerman's Surgical Pathology. 10th
ed., Vol. 1. St. Louis, Missourri; Mosby-Year Book Inc.; 2010. p. 291-9.
Muchiri M. Demographic study of nasopharyngeal carcinoma in a hospital setting. East Afr Med J 2008;85:406-11.
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