NASOPHARYNGEAL CARCINOMA AT THE AHMADU BELLO UNIVERSITY TEACHING HOSPITAL, ZARIA: A TWENTY TWO YEAR HISTOPATHOLOGICAL REVIEW (1992-2013)

Abstract

Nasopharyngeal Carcinoma (NPC) is an uncommon cancer with unique geographical variations
and strong association with Epstein-Barr Virus (EBV). 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, histopathological patterns and EBV status of
NPC seen over a period of twenty two years, from 1992 to 2013.

It was a retrospective study of all NPCs diagnosed at the Department of Pathology, Ahmadu
Bello University Teaching Hospital (ABUTH) from 1st January 1992 to 31st December 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 Organisation (WHO) classification. EBV detection was done using
Immunohistochemistry (IHC) for EBV latent membrane protein-1 (LMP-1).

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,
Non-keratinizing Carcinoma (NKC) was the commonest (94.6%) followed by Keratinizing
Squamous Cell Carcinoma (KSCC, 4.5%) and a single case of Basaloid Squamous Cell
Carcinomas (BSCC, 0.9%). 79.4% of NKC were Undifferentiated, 12.7% Differentiated and
7.9% were Mixed. Also, 44.4% were of Regaud type growth pattern, 34.9% Schmincke type and
20.6% were Mixed. EBV LMP-I IHC was positive in 77.3% while 22.7% were negative. NKC
xv

showed 77.8% positivity while KSCC showed 66.7% positivity. The nasopharynx was the
commonest site of surgical biopsy (57.1%) followed by the nasal cavity (17.9%) and cervical
lymph node 11.6%.

NPC showed a low frequency though the incidence has increased lately. It showed 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. NPC showed a strong
association with EBV irrespective of histological type. A significant number of biopsies were
from sites outside the nasopharynx, suggestive of advanced disease with poor prognosis.