HISTOPATHOLOGICAL ANALYSIS OF MALIGNANT LYMPH NODE
LESIONS IN PORT HARCOURT, NIGERIA
BY
OBIORAH C.C
MBBS (NIG), FMCPath
GOGO-ABITE M
MBBS, FWACS(lab med)
OKORO P.E
MBBS, FWACS, FICS
ANATOMICAL PATHOLOGY DEPARTMENT
UNIVERSITY OF PORT HARCOURT
TEACHING HOSPITAL
PORT HARCOURT
Correspondences To:
OBIORAH C.C
Anatomical Pathology Department
University of Port Harcourt
Teaching Hospital
Port Harcourt
e-mail:christopherobiorah@yahoo.com
07030475312
1
ABSTRACT
AIMS:
This study reviews and characterizes malignant lesions of lymph nodes seen
among patients attending the University of Port Harcourt Teaching Hospital
(UPTH), which is the reference cancer center in the Niger Delta region. It further
evaluates how well the tasks of the pathologist are carried out in the centre and
highlights limitations to actualizing the tasks.
MATERIALS AND METHODS:
The study is a five-year retrospective one undertaken at the Anatomical Pathology
department of the University of Port Harcourt Teaching Hospital, Port Harcourt,
Nigeria.
Archived hematoxylin and eosin (H & E) stained slides of processed malignant
lymph node lesions seen between 2006 and 2010 were studied. Accompanying
request forms were reviewed for patients’ age, sex, diagnosis and site. Nodes
accompanying malignant lesions were noted and compared histologically with the
lesions of the primary tissue for consistency of morphologic features. The data
obtained were analyzed using SPSS soft ware version 17.0
RESULTS:
Malignant lesions were recorded in 118 cases (49.8%) out of 237 lymph node
biopsies processed during the period.
There were 54 males and 64 females. Metastatic lesions constituted 59.3% while
primary lymphoid malignancies constituted 40.7%. The age range was 2 to 72
years and the mean was 46.5 years. Peak age range was 60-69 years.
Patients younger than 30 years constituted 23% in Non-Hodgkin lymphoma (NHL)
and 72.7% in Hodgkin lymphoma (HL) while for metastatic lesions, they constituted
15.3%.
In descending order the primaries of the metastases were from adenocarcinomas
of the breast, various sarcomas, squamous cell carcinoma, melanocarcinoma and
carcinoid tumor. Seventy-one percent of NHL were of high grade, while 29% was
of intermediate grade. Nine (56.3%) of the HL were of the nodular sclerosing type
while 4 (25%) were of lymphocyte depleted and 2 (12.5%) were of lymphocyte rich
types.
The axillary lymph node was the commonest node involved in metastases followed
by cervical node.
2
CONCLUSION
Metastatic lesions constitute the bulk of malignant lymph node lesions presenting
in the Niger Delta region of Nigeria. Commonest primary lesions are from the
breast in females. Implementing cancer-screening programmes, public
enlightenment and population based cancer registration will reduce cancer
prevalence in the region.
Practice of pathology and patient care will be improved by the provision of
immunohistochemisty and other molecular pathology techniques needed to
increase the accuracy of pathologic diagnosis.
KEY WORDS: Lymph node, malignant, metastases, Niger Delta
3
INTRODUCTION
Lymphadenopathies are common presentations in clinical practice. Various studies
on the pathology of lymph nodes show preponderance of malignant lesions 1-6.
Malignant lymph node lesions may be of primary lymphoid type or metastatic.
Lymph nodes constitute the most common site of metastatic malignancy and
sometimes manifest the first clinical signs of the disease 7, 8. Any malignant tumor
can give rise to lymph node metastases, but the incidence varies greatly
depending on the tumor type. Metastatic tumors are common with carcinomas,
malignant melanomas and germ cell tumor, and rare with sarcomas 9.
Among the lymphoid malignancies, Non-Hodgkin lymphoma (NHL) occurs more
commonly than Hodgkin lymphoma (HL). 10 - 13.
Burkitts lymphoma (BL) is known to have distinct epidemiological, clinical and
microscopic features and is thus considered by some authors as separate entity
from NHL 14, 15. Most cases occur in childhood and presentation, as peripheral
lymphadenopathy is rare.
The task of the pathologist among others is to identify the presence of malignant
process in lymph nodes and establish whether it is metastatic or not. If metastatic,
the Pathologist should provide an estimate of the amount, microscopic type and
possible source. 16.
This study attempts to review and histologically characterize malignant lesions of
enlarged lymph nodes seen among patients attending the University of Port
Harcourt Teaching Hospital (UPTH). It further evaluates how well the tasks of the
pathologist in determining primary sources of metastatic lymph node lesions are
carried out in UPTH and highlights limitations to actualizing the task.
4
MATERIALS AND METHODS:
The study is a five-year retrospective one undertaken at the Anatomical Pathology
department of the University of Port Harcourt Teaching Hospital, Port Harcourt
Nigeria.
The tissue registers of the department were reviewed for lymph node tissue
specimens received and processed between January 2006 and December 2010.
Archived hematoxylin and eosin (H & E) stained slides of the identified cases were
studied. Emphasis was laid on malignant lesions.
The accompanying request forms and duplicate copies of the issued reports were
reviewed for patients’ age, sex, diagnosis and specific site of the component lymph
node tissue. Lymph nodes accompanying malignant lesions were noted and
compared histologically with the lesions of the primary tissue for consistency of
morphologic features. Where necessary new H & E stained slides were made from
paraffin embedded tissue blocks.
The data obtained were analyzed using SPSS soft ware version 17.0
5
RESULTS:
A total of 237 lymph node biopsies were reviewed, out of which malignant lesions
were recorded in 118 cases (49.8%)
There were 54 males and 64 females, giving a male female ratio of 1:1.2.
Metastatic lesions constituted the majority with 70 cases (59.3%) while primary
lymphoid malignancies constituted the rest 48 cases (40.7%). Metastatic lesions
occurred more in the females, than primary lymphoid malignancies with 48 cases
(40.7%) and 22 cases (18.6%) respectively while males recorded more of primary
lymphoid malignancies with 32 cases (27.1%) as against 16 cases (13.6%) of
metastatic lesions.
The data on the ages of the patients were incomplete, as 22 cases (18.6%) had no
information on age. The age data for this study was thus derived from the
remaining 96 cases (81.4%). The range was 2 to 72 years and the mean was 46.5
years. Generally, the occurrence of malignant lesions increased with age, being
least at age range 0-9 years with 6 cases (5.1%) and highest at age range 60-69
with 27 cases (22.9%). Between these extremes, the prevalence of malignancies
considerably increased with age and declined progressively beyond 69 years. This
increment with age is observed in both lymphoid and metastatic lesions.
Cumulatively, 0-19 years recorded the least with 14 cases (11.9%) followed by 2049 years with 32 cases (27.1%) and highest occurrence was in patients of 50 years
and above with 50 cases (42.4%).
Children and young adolescents of ages 0-19 recorded more of lymphoid
malignancies with 8 cases (6.8%) than metastases with 6 cases (5.1%) while in
adults of 20 years and above, there were more cases of metastases to lymph
nodes with 49 cases (41.5%) than 33 cases (28%) of primary lymphoid
malignancies. Specifically, the mean age for metastatic lesions was 49.1 years,
while for NHL it was 49.9 years. Also it was 26.3 years for HL and 4.3 years for BL.
For NHL, Patients younger than 30 years constituted 23% while those 30 years
and older constituted 77%. For HL, patients less than 30 years constituted 72.7%
while those 30 years and above constituted 27.3%. For metastatic lesions, it was
15.3% and 84.7% respectively for similar age groups.
Of the 70 metastatic lesions, the primary sites of 41 cases (34.7%) were not
determined owing to non-availability of molecular pathology diagnostic aid in this
center. The 29 cases (24.6%) with confirmed primary sites were determined by
directly comparing the H&E stained slides of both primary and metastatic lesions.
Among the metastases, adenocarcinoma was the commonest morphologic pattern
seen, with 57 cases (81.4%). It occurred as 15 cases (26.3%) in the males and 42
cases (73.7%) in the females. Adenocarcinoma was followed by sarcoma with 5
cases (7.1%) occurring as 3 cases (60%) in the females and 2 cases (40%) in
males. Squamous cell carcinoma and melanocarcinoma were next with 4 cases
(5.7%) and 3 cases (4.3%) respectively. These occurred as 3 cases (75%) and 2
cases (66.7%) in the males respectively and 1 case each (25%) and (33.3%) in the
females. Carcinoid was the least morphologic pattern with 1 case (1.4%), seen in a
female.
6
Of the 31 NHL, 22 (71%) were of high grade, while 9 (29%) were of intermediate
grade. Nine (56.3%) of the HL were of the nodular sclerosing type while 4 (25%)
were of lymphocyte depleted and 2 (12.5%) were of lymphocyte rich types.
The axillary lymph node was the commonest node involved in metastases with 26
cases (22.0%) followed by cervical node with 9 cases (7.6%). Supraclavicular was
the least involved with 1 case of nasopharyngeal carcinoma.
Of the 11 determined primaries that metastasized to the axillary lymph node, 8
cases (72.7%) were from the breast (all females). The 3 cases of
melanocarcinoma metastases metastasized to inguinal nodes.
Of the 31 cases of NHL, 17 cases (54.8%) were from un-indicated lymph node sites, while
7 cases (22.6%) were diagnosed in biopsies of cervical lymph node and 3 (2.5%) in
mesenteric nodes.
7
TABLE 1
SEX AND AGE GROUP DISTRIBUTION OF MALIGNANT LYMPH NODE LESIONS.
Diagnosis
Male Female Unknown 0-9
10-19 20-29 30-39
age
years years years years
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Undefined
metastases
Prostate carcinoma
metastasis
Breast
carcinoma
metastases
Nephroblastoma
metastases
Rhadomyosarcoma
metastases
Nasopharyngeal
carcinoma metastases
Thyroid carcinoma
metastasis
Colonic carcinoma
metastasis
Angiosarcoma
metastasis
Carcinoid
tumour
metastasis
Squamous
cell
carcinoma metastases
Melanoma
metastases
Liver cell carcinoma
metastasis
Non-Hodgkin
Lymphoma
Hodgkin Lymphoma
16 Burkitts Lymphoma
Total
40-49
years
50-59
years
60-69
years
70-79
years
12
29
12
-
2
1
5
6
4
10
1
80
and
above
-
Total
1
-
-
-
-
-
-
-
-
1
-
-
2
-
8
1
-
-
1
1
1
3
1
-
-
16
-
3
-
1
1
1
-
-
-
-
-
-
6
1
3
1
1
-
-
-
1
-
1
-
-
8
1
-
-
-
-
-
-
-
-
1
-
-
2
-
1
-
-
-
-
-
-
-
1
-
-
2
-
1
-
-
-
1
-
-
-
-
-
-
2
1
-
-
-
-
-
1
-
-
-
-
-
2
-
1
-
-
-
-
-
-
-
-
1
-
2
3
1
-
-
2
-
-
-
-
1
1
-
8
2
1
1
-
-
-
-
-
-
1
-
-
5
1
-
-
-
-
-
-
-
1
-
-
-
2
22
9
5
2
0
3
1
1
9
7
3
-
62
7
7
2
-
3
5
3
-
-
1
-
-
28 8
3
54
64
22
3
7
8
12
11
9
17
25
6
-
6
235
82
Chart showing Sex Distribution of Malignant Lymph node
Lesions
1
2
9
DISCUSSION:
In this study, malignant lesions which, constituted 49.8% compares favorably with
the 49.2% and 48.3% observed by Adeniji 1 and Oluwole 2 in similar studies carried
out at Ilorin and Ile-Ife respectively. It also compares well with the 52.8% and
47.8%, recorded by Olu-Eddo 3 in Benin and Anunobi 4 in Lagos respectively. In
Iran, Nada et al 5 observed malignant lesions in 44.7% of lymph node biopsies,
while in Zimbabwe, Sibanda 6 observed similar lesions in 19.4% of lymph node
biopsies.
The inference from our study and those sited above is a high prevalence of
malignant lesions of the lymph nodes in Nigeria. This is most noted in our study
and that of Olu-Eddo 3, both studies were carried out in different cities of the same
geopolitical region of Niger Delta - a region noted for decades of oil exploration and
production with attendant environmental pollution. A recent United Nations
Environment Programme (UNEP) report on oil pollution in Ogoni land 26 showed
exposure of some oil company host communities to very high levels of the
carcinogenic agent-benzene through drinking water source contamination. This
report strengthens the possibility that the exposure of the inhabitants and
indigenes of this region to oil pollution may be contributory to the high rate of
malignancies in the region as witnessed in this study. Strengthening population
based cancer registration in the region will further elucidate the incidence and
prevalence of malignancies in the region.
Further more, findings of this study suggest that about half of the times, chances
are that patients presenting with enlarged lymph nodes in UPTH may be having
malignant lesions. This is clinically important and requires that clinicians, especially
surgeons should biopsy all such lymph nodes to increase the odds of detecting
possible malignancy in such patients. Consequently, the empirical treatment with
anti-tuberculosis drugs without biopsy to patients presenting with peripheral
lymphadenopathy, offered by some clinicians may need to be reconsidered.
The male to female ratio observed in this study was 1:1.2. Although Anunobi 4 in
a similar study in Lagos also observed more females than males most other
researchers reported more males than females. The variation in prevalence with
sex may be a reflection of the demographic features of the study areas.
Fifty-nine percent (59.3%) of the malignant lesions were metastases from different
primary sites to the nodes while the rest were lymphoid malignancies. This figure is
higher than the 26.5% reported by Olu-Eddo. 3 There is inconsistency in reports on
the prevalence of metastatic versus lymphoid malignancies of the lymph node. Our
study found a preponderance of metastatic over lymphoid malignancies as
Anunobi’s 4 finding in LUTH, with 33.6% metastases as against 14.2% cases of
lymphomas. Adeniji 1 in Ilorin observed 19.3% metastases and 31.5% lymphomas
while Okolo 17 observed 41.8% lymphomas and 1.7% metastases. Ochicha 18 in
Kano found 19.1% metastases and 23.6% lymphomas. Consequently, the odds of
detecting metastatic lesions in lymph node biopsies of patients attending UPTH is
high and agrees with literature documentation that lymph nodes constitute the
most common site of metastatic malignancy and sometimes constitute the mode of
10
presentation of the primary lesion. Such lesions may be from an occult or clinically
apparent primary site. It is quite tasking for the pathologist to decipher the primary
site of a metastatic lesion from an occult carcinoma without the use of
immunohistochemistry and other molecular pathology techniques. These
techniques are currently lacking in some histopathology laboratories in Nigeria
including our study center.
This study observed that while females showed more of metastatic lesions, males
showed more of primary lymphoid lesions. The reason for this disproportionate
finding is not readily adducible. Nonetheless, the possible clinical interpretation is
that most female carcinoma patients present in advanced clinical stages. Lack of
awareness and screening programmes are the most plausible reasons for this.
Efforts should be intensified to increase the awareness level and provide cancer
screening opportunities to females, particularly the rural dwellers who constitute
the bulk of such late presenting patients. Contrary to females, males presented
with more primary lymphoid malignancies than metastases.
Although the overall mean age in this study was 46.5 years, the specific mean
ages for metastatic and NHL patients were 49.1 years and 49.9 years respectively
while for HL and BL it was 26.3 years and 4.3 years respectively. This finding is
consistent with Adeniji’s 1 report that the incidence of malignancy increases after
40 years, and agrees with the opinion expressed by Thomas 19 in Ibadan that
except HL, which peak in children and adolescents, NHL and metastatic lesions
peak after 40 years among Nigerians. The mean age of 26.3 years for HL in this
study supports Thomas assertion and is consistent with general literature
documentation that HL occur more in younger patients than NHL. Guttenshohn 20
postulated a correlation between the state of economic development of a nation
and the incidence of childhood HL. Thus the poorly developed economic state of
Nigeria may in part explain why the disease is commoner in children and young
adults in our study. Two-thirds of NHL patients were >/ 30 years while same
proportion in HL patients were </ 30 years.
Comparatively, Sibanda 6 in his study in Zimbabwe reported mean age of
42.07years and 52.35 for females and males respectively for metastatic lesions of
the lymph node. He also noted that 75% of metastatic disease patients were >/ 40
years.
The 4.3 years mean obtained for BL in this study is consistent with existing body
of knowledge that BL is a common childhood tumor.
In both metastatic and lymphoid malignancies, incidence increased with age, being
least at 0-9 years and highest at 60-69 years age-range respectively. This is
consistent with Adenijis 1 observation in Ilorin that for NHL, incidence gradually
rises from early adulthood and middle age and peaks in the elderly. It also agrees
with Attahs 21 observation in Ibadan that metastatic tumors occur mainly in patients
of 20 years and above. This concurs with the report that age is an important
influence in the likelihood of an individual being afflicted with cancer 22.
11
In children, lymphoid malignancies occurred more than metastatic lesions while in
adults metastatic lesions occurred more than primary lymphoid malignancies. We
have no ready explanation for this observation.
We could not determine the primary sites of origin of 58.6% of the metastases in
this study. This is well beyond the 36.6% undetermined in Ilorin by Adeniji 1. This
proportion of undermined metastases is attributable to the non-availability of
immunohistochemistry and other molecular pathology techniques in our center.
However, despite technological advancement among Western nations it is not
uncommon to encounter cases with challenging differentials in histopathology
practice, hence Krementz 23 in a study in Luisiana, USA observed that despite the
advanced diagnostic resources, in over half of metastatic lymphadenopathy the
primary source is not known. The task of the Pathologist is not only to identify the
presence of malignant process in the node but establish whether it is metastatic or
not and confirm the primary site(s) of the metastases 16. In our case, this task is
not satisfactorily fulfilled owing to poor diagnostic infrastructure. This illustrates the
frustrations faced daily by Pathologists practicing in most developing and
underdeveloped nations where necessary diagnostic tools are not available and
affordable. This also has negative consequence in the quality of care given to
patients by clinicians who rely on Pathologists judgments for patients care.
Carcinoma with 32.9% was the most frequent metastatic lesion, followed by
sarcomas with 7.1% and carcinoid tumor with1.4%. This finding is consistent with
the existing knowledge that carcinomas metastasize much more frequently to
lymph nodes than sarcomas and other tumor types 9. Of the carcinomas, primary
lesions from the breast were the commonest. The 34.8% metastatic rate from
breast cancer observed in this study proximate the 38% found in Kano by Ochicha
18 and is reflective of the high scourge of breast cancer in females. More
awareness for self-breast examination and other cancer screening programmes
need to be embarked upon, particularly among rural dwellers that constitute bulk of
the patients.
The preponderance of NHL over HL in this study is consistent with reports by
Hartage 10 and Croves 24. Furthermore, in the USA and Western Europe, HL
comprises only about 20-30% of all malignant lymphomas and even much lower
percentage in Japan and other Oriental countries 25.
That most of the NHL was of high grade type is also consistent with Ochichas 18
finding in Kano and keeps with the overall observation that most malignancies in
our study environment present late and thus portend poor prognosis.
The axillary lymph node was the commonest node involved in metastasis in this
study. This is in keeping with the observation that the breast, which preferentially
drains to the axillary lymph nodes, was the commonest metastatic site identified in
this study. This also agrees with Oluwole’s 2 finding that axillary nodes were the
most frequent sites for breast metastases. The 3 cases of melanocarcinomas in
this study metastasized to inguinal nodes. Oluwole also observed inguinal nodes
as the most frequent site for melanoma metastases.
12
CONCLUSION
Metastatic lesions constitute the bulk of malignant lymph node lesions presenting
in the Niger Delta region of Nigeria. Commonest primary lesions are from the
breast in females. Implementing cancer-screening programmes, public
enlightenment and population based cancer registration will reduce cancer
prevalence in the region.
Practice of pathology and patient care will be improved by the provision of
immunohistochemisty and other molecular pathology techniques needed to
increase the accuracy of pathologic diagnosis.
13
REFERENCE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10
11.
12.
13.
14.
15.
16.
17.
18.
19.
Adeniji KA, Anjorin AS. Peripheral lymphadenopathy in Nigeria. Afr J Med
med Sci 2000; 29:233-237
Oluwole SF, Odesanmi WO, Kalidasa AM. Peripheral lymphadenopathy in
Nigeria. Acta Trop 1985; 42:87-96
Olu-Eddo AN, Ohanaka CE. Peripheral lymphadenopathy in Nigerian adults.
J Pak Med Assoc.2006 56 (9): 405-408.
Anunobi CC, Banjo AA, Abdulkareem FB, Daramola AO, Abudu EK. Review
of histopathological patterns of superfifial lymph node diseases in
Lagos(1991-2004). Niger Postgrad Med J. 2008; 15(4) 243-246
Nada AA, Amer SA, Maad MS, Esam AA. Fine needle aspiration cytology
versus histopathology in diagnosing lymph node lesions. East Med Health
J. 1996; 2 : 320-325.
Sibanda EN, Stanczuk G. Lymphnode pathology in Zimbabwe: a review of
2194 specimens. Quart J Med. 1993; 86:811-817.
Didlolker MS, Fanous N, Elias EG, et al.: Metastatic carcinomas from occult
primary tumours. A study of 254 patients. Ann Surg 1977. 186:628-630,.
Haagensen CD, Feind CR, Herter FP, Slanetz CA Jr, Weinberg JA: The
lymphatics in cancer. Philadelphia, 1972, WB Saunders Co.
Lymph nodes in: Rosai J Ackerman’s surgical pathology. 9 th Edition Elsevier
inc; 2004.
Hartage P, Devessa SS, Fraumeni JF. Hodgkin's and non-Hodgkin's
lymphoma. Cancer Surv 1994; 19-20:423-433
Obafunwa JO, Akinsete I. Malignant lymphoma in Jos, Nigeria: a ten-year
study. Centr Afr J Med 1992; 38:17-25
Adedeji MO. Malignant lymphoma in Benin City, Nigeria. East Afr Med J
1989; 66:134-140
Pindiga HU, Ahmed SG. Histological types of nodal lymphoma in
northeastern Nigeria. Sahel Medical Journal (Nigeria) 2002; 5:43-46
Banks PM, Arseneau JC, Gralnick HR, Cannellos GP, DeVita VT Jr, Berard
CW: American Burkitt's lymphoma. A clinicopathologic study of 30 cases. II.
Pathologic correlations. Am J Med 58:322-329, 1975.
Arseneau JC, Canellos GP, Banks PM, Berard CW, Gralnick HR, DeVita VT
Jr: American Burkitt's lymphoma. A clinicopathologic study of 30 cases. I.
Clinical factors relating to prolonged survival. Am J Med 58:314-321, 1975.
Mackay B, Ordoñez NG: The role of the pathologist in the evaluation of
poorly differentiated tumors and metastatic tumors of unknown origin. In Fer
MF, Greco FA, Oldham RK, eds: Poorly differentiated neoplasms and
tumors of unknown origin, New York, 1986, Grune & Stratton, Inc.
Okolo SN, Nwanna EJ, Mohammed AZ. Histopathologic diagnosis of
lyphadenopathy in children in Jos, Nigeria. Niger Postgrad Med J 2003;
10(3) 165-167.
Ochicha O, Edino ST, Mohammed AZ, Umar AB, Atanda AT. Pathology of
peripheral lymph node biopsies in Kano, Northern Nigeria. Ann Afr Med.
2007;6: 104-108.
Thomas JO, Ladipo JK, Yawe T. Histopathology of lymphadenopathy in a
tropical country. East Afr Med J 1995; 12:703-705.
14
20.
21
22
23
24
25
26
Guttenshohn N, Cole P. Epidemiology of Hodgkins disease in the young. Int
J Cancer. 1997; 19: 595-604.
Attah EB. Peripheral lymphadenopathy in Nigeria. Trop Geogr Med. 1974;
26: 257-260.
Aster JC. Diseases of white blood cells, lymph nodes, spleen and thymus.
In: Kumar V, Abbas AK, Fausto N, Robins SL, Cotran R.S. Pathologic Basis
of Disease. 7th Edition. Philadelphia: Elsevier Saunders; 2004.p.661-709.
Krementz ET, Cerise EJ, Ciaravella JM, Morgan LR. Metastasis of
undetermined source. Cancer NY. 1977; 27: 289-300.
Croves FD, Linet MS, Travis LB, Devessa SS. Cancer Survey Series; NonHodgkins lymphoma incidence by histological type in USA from 1978-1995.
J Natl Cancer Inst 2000; 92 :1240-1251
Akazaki K, Wakasa H: Frequency of lymphoreticular tumors and leukemias
in Japan. J Natl Cancer Inst. 1974; 52:339-343.
United Nations Environment Programme (UNEP) Nairobi, Kenya. 2011.
Environmental Assessment of Ogoniland. ISBN: 978-92-807-3130-9.
15
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