2004 Summer Meeting - Amsterdam - The Pathological Society of ...

169
Congenital Cellular Mesoblastic Nephroma: Low Sensitivity
for Detection of the ETV6-NTRK3 Fusion Transcript in
Archival Paraffin-Embedded Material
NJ Sebire 1 , S Gibson 1 , J Anderson 2 , M Malone 1 , AD
Ramsay 1
1 Department of Paediatric Pathology, Great Ormond Street Hospital,
London, United Kingdom, 2 Department of Molecular Oncology, Great
Ormond Street Hospital, London, United Kingdom
Introduction: Congenital mesoblastic nephroma (CMN) is a common renal
tumour of infancy in which the cellular variant has been reported to be
associated with ETV6-NTRK3 fusion transcript also described in infantile
fibrosarcoma (IFS). Recently, this fusion transcript has been detected from
formalin fixed paraffin-embedded archival samples of both CMN and IFS with
varying success. The aim of this study is to examine the use of RT-PCR for
detection of the ETV6-NTRK3 fusion transcript in archival cases of formalinfixed,
paraffin-embedded CMN, cellular, mixed and classic types.
Methods. Cases of CMN in whom paraffin blocks were available were
anonymised, H&E sections examined by two pathologists and classified as
classic, cellular or mixed type. In each case, sections from a representative
block were cut, RNA extracted and RT-PCR carried out according to a standard
protocol to detect the ETV6-NTRK3 fusion transcript.
Results. In all 13 cases of CMN, adequate detection of ß-actin housekeeper
gene product was obtained confirming RNA viability of fragments up to 200bp
in size. Only two cases demonstrated presence of the ETV6-NTRK3 fusion
transcript including one of the four cases of CMN (25%), one of the four cases
of mixed CMN (25%) but none of the five cases of classical CMN.
Conclusion. In paraffin embedded archival material, the ETV6-NTRK3 fusion
transcript is detectable in a minority of cases of cellular and mixed type CMN
using rt-PCR. The finding of a positive result provides diagnostic confirmation
but, as with many molecular techniques, a negative result does not exclude the
diagnosis, particularly if fresh tissue is not available.
170
An Audit of the Clinical Usefulness of Examining Bone
Marrow Trephine Biopsies at Multiple Levels with CD56
Immunohistochemistry for Staging of Neuroblastic Tumours
NJ Sebire , D Rampling , S Williams , M Malone , AD Ramsay
Department of Paediatric Pathology, Great Ormond Street Hospital,
London, United Kingdom
Introduction: Detection of metastatic disease is important for staging and
treatment modification in cases of paediatric neuroblastic tumour. In one case,
neuroblastic tumour was not present on the initial trephine sections but a small
focus became apparent in a subsequent level using immunohistochemistry.
Following this case, our protocol has been to perform examination of trephine
specimens for this indication at several levels with CD56
immunohistochemistry on each level.
Methods. A retrospective review of all cases of bone marrow trephine biopsies
examined for the indication of neuroblastic tumour was carried out over a 17
month period.
Results. There were 56 specimens examined for determination of involvement
by neuroblastic tumour during the study period. In 12 cases (21%), neuroblastic
tumour was present and in 44 cases (79%) no neuroblastic tumour was present.
There were no cases in which examination at multiple levels or use of routine
immunohistochemistry aided either diagnosis in this series. If the index case is
included, levels and immunostaining provide additional diagnostic information
in a maximum of only 1.7% (95% CI 0%-9%) of such cases. The cost of levels
and immunostaining (based on WELCAN units) is >200% greater than routine
processing and staining, meaning it would cost at least £24,000 to possibly
detect one extra case of marrow involvement. We therefore believe this is not a
cost-effective protocol.
Conclusion. The routine use of multiple levels and CD56
immunohistochemistry in bone marrow trephine biopsies for assessment of
involvement by neuroblastic tumour is not cost-effective and only specifically
indicated use of these techniques is recommended.
171
Immunohistochemical Findings in Embryonal ‘Small Round
Cell’ Tumours with Molecular Diagnostic Confirmation
NJ Sebire , S Gibson , D Rampling , S Williams , M Malone ,
AD Ramsay
Department of Paediatric Pathology, Great Ormond Street Hospital,
London, United Kingdom
Introduction: Diagnosis of pediatric tumors relies heavily on
immunohistochemical staining of small tissue biopsies since many entities
share a ‘small blue cell’ phenotype. Since introduction of molecular genetic
analysis for detection of gene fusion products we have noted that tumors with
proven molecular diagnoses can exhibit unusual patterns of
immunohistochemical staining.
Methods. A panel of immunohistochemical stains was performed on sections
from paediatric tumors with a ‘small blue cell’ phenotype in which molecular
diagnostic confirmation was available. (S100, CD56, NB84, CD99 (MIC2),
Bcl-2, CD117, CD34, Desmin, MNF116 and WT1).
Results. In 370 sections from 37 cases, all PNETs, with and without the
presence of t(11;22), demonstrated uniform membranous staining with CD99
(MIC2) and focal staining with CD56, NB84, MNF116 and WT1. All
rhabdomyosarcomas, both alveolar and embryonal, demonstrated uniform
Desmin, CD56 and cytoplasmic WT1 immunostaining. DSRCTs showed
positive cytokeratin staining, with half having ‘dot-like’ cytoplasmic desmin
and WT1 positivity; some showed focal positivity for NB84, CD99 and Bcl-2.
‘Undifferentiated’ sarcomas showed the widest range of staining with no
marker staining all cases. Neuroblastomas exhibited uniform strong staining for
CD56 and NB84 and marked cytoplasmic Bcl-2 positivity. Blastematous Wilms
tumors showed uniform strong membranous staining for CD56, uniform
cytoplasmic staining for Bcl-2 and nuclear expression of WT1.
Conclusion. Embryonal pediatric malignancies can demonstrate apparently
non-specific expression patterns for several antigens, which may reflect
developmental immaturity rather than specific differentiation pathways.
172
Surgical Pathology of the Paediatric Larynx: A 15 Year
Survey in a Specialist Children’s’ Hospital
B Vadgama , A D Ramsay , M Malone , N J Sebire
Great Ormond Street Hospital for Children, London, United Kingdom
Examination of laryngeal specimens constitutes a significant proportion of the
general adult surgical workload, and many cases involve epithelial neoplasia. In
children the clinical problems and pathological lesions involving the larynx are
quite different. We have examined the spectrum of laryngeal pathology seen in
a tertiary referral specialist paediatric pathology unit.
A total of 256 laryngeal and epiglottic specimens from 212 patients
were retrieved from the pathology archives for the 15 year period 1998 to 2003.
31 patients (14.6%) had more than one biopsy and the patients’ age at the time
of biopsy ranged from one day to 17 years old (median 2.8 years). The male to
female ratio was 1.3:1. Laryngeal specimens constituted less than 1.5% of the
departmental workload.
The most frequent clinical indications were laryngomalacia (18),
congenital lesions (15), cysts (14) and hoarse voice (8). The majority of
specimens (254 cases) were biopsies and the vocal cord was the most common
site. There was a total laryngectomy for fibrotic stenosis secondary to caustic
soda ingestion, and a partial laryngectomy for paraganglioma. The commonest
diagnoses were papilloma (48); intubation granuloma (39); cyst (20); chronic
inflammation (22); acute inflammation (10 - 3 with necrosis and 1 with fungal
hyphae); and 8 each of vocal cord polyps and haemangiomas. Less common
conditions included rhabdomyosarcoma (3), granular cell tumour (2), severe
dysplasia (1), and lipid proteinosis (1). No abnormality was seen in 20 cases.
We concluded that laryngeal pathology is relatively infrequent in
the paediatric age group, but that a variety of conditions can occur at this site
and that these can arise from both the epithelial and the stromal components of
the larynx.
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