IMMUNOHISTOCHEMICAL CHARACTERIZATION OF SMALL ROUND BLUE CELL TUMOURS OF CHILDHOOD AT ILE-IFE, NIGERIA. A TEN YEAR RETROSPECTIVE STUDY (JAN. 2002-FEB. 2011)

Abstract

Background: Immunohistochemistry is an important investigative
tool used in making diagnosis of Small Round Blue Cell Tumours. These
immunostains when used as a routine technique in correlation with
clinical site of tumours and morphology will permit accurate and specific
diagnosis of these undifferentiated tumours to be made. The aim of this
study is to carry out a ten-year retrospective analysis of the
histopathological and immunohistochemical features of small round blue
cell tumours in OAUTHC.

Method: We retrospectively reviewed our data of histological results over
the last ten years and retrieved all the diagnosed cases of small round
blue cell tumours over this period. The haematoxylin and eosin stained
slides were reviewed to make the diagnosis and different
immunohistochemical stains were done on these tumours depending on
the morphology and clinical site of the tumour to confirm the histological
sub-types.
Results: A total of one hundred and thirty two (132) cases of childhood
tumour were documented in the histopathology records over ten years
period, of which one hundred and nine (109) were small round blue cell

tumours (SRBCT), but only eighty five (85) cases that fulfilled the
inclusion criteria were analysed using immunohistochemistry. The
remaining twenty four (24) cases were missing tissue blocks, tissues with
missed diagnoses and blocks without adequate tissue for
immunohistochemistry. The age range of presentation was 0-15 years
(Mean 5.98±3.964 year S.D.). Retinoblastoma and Wilms’ tumours were
the commonest histological sub-types with a percentage of 20.0% each
followed by Burkitt lymphoma with a percentage of 17.6%.
Rhabdomyosarcoma was the fourth most common SRBCT and the only
soft tissue sarcoma found with a frequency of 9.8%. The least
represented was supra-tentorial CNS-PNET with percentage of 1.2%.
Eighty five blocks of SRBCT were subjected to different
immunohistochemistry. Of all these tumours 36 cases had a change in
diagnosis. Of these 36 cases, 23 cases had an initial, pre
immunohistochemical umbrella diagnosis ranging from NHL, SRBCT to
no pathological diagnosis at all. Seven (7) cases with initial diagnosis
ranging from Ewing’s sarcoma (1 case), retinoblastoma (1 case) to
rhabdomyosarcoma (5 cases) were finally confirmed with immunostains
as Burkitt lymphoma (BL) while one case of BL was finally confirmed as
rhabdomyosarcoma. The last five of the 36 cases were totally non
neoplastic lesions but had histology diagnosis ranging from NHL, spinal
cell sarcoma to periosteal osteosarcoma. The last 2 had clinical diagnosis
of Wilms’ tumour and retinoblastoma but histology diagnosis of
unclassified SRBCTs. The immunostains done on these cases revealed
erythroid hyperplasia with dyserythropoiesis, cellular neurofibroma,
fibrous dysplasia, reactive follicular hyperplasia and normal retinal
tissue.
Conclusion: In conclusion, the application of immunohistochemistry in
this study has shown a significant improvement in the diagnostic
accuracy of these undifferentiated tumours. Again, if immunostaining
were routinely available, accurate diagnosis will be made and therefore
appropriate treatment will be given. This will help to improve health
status of these children and reduce unnecessary wastage of
funds/resources invested on chemotherapy given on cases of
unconfirmed diagnosis.

IMMUNOHISTOCHEMICAL CHARACTERIZATION OF SMALL ROUND BLUE CELL TUMOURS OF CHILDHOOD AT ILE-IFE, NIGERIA. A TEN YEAR RETROSPECTIVE STUDY (JAN. 2002-FEB. 2011)