Primary Primitive Neuroectodermal Tumor (PPNET ... - aioseducation

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This paper was conferred with the BEST PAPER of ORBIT/ PLASTIC-I Session.
Primary Primitive Neuroectodermal Tumor (PPNET)
of The Orbit, A 10 Year Review
Dr. Rachna Meel, Dr. Seema Kashyap, Dr. Neelam Pushker, Dr. Sameer
Bakhshi, Dr. Seema Sen, Dr. Mandeep Singh Bajaj
Purpose: Primitive neuroectodermal tumors (PNET) are soft tissue sarcomas characterized
by chromosome translocation t (11;22) (q24:q12) and neuroectodermal differentiation. We
report 11 cases of orbital PNET. Method: Retrospective analysis of demographic, clinical
and imaging details of orbital PNETs diagnosed between 1999- 2008. Histopathology and
immunohistochemistry were reviewed. Treatment outcome was studied where ever available.
Result: Age of patients was 1.5 months - 20 years. Duration of symptoms ranged from 10
days-l0 months. Chief complaint was rapidly progressive proptosis in 8 and lid mass in 3 cases.
There was extraorbital involvement in 6 and lymph node metastasis in 1 case. Light microscopy
revealed malignant round cell tumor which was confirmed on immunohistochemistry. Amongst
7 patients with follow up, 4 survived with no evidence of tumor at last follow up. Conclusion:
PNET of orbit is a rare, aggressive tumor with scanty literature and no set guidelines for
treatment.
Primitive neuroectodermal tumors (PNET) are described as a family of
soft tissue sarcomas characterized by chromosome translocation t (11;22)
(q24:q12) and showing varying degrees of neuroectodermal differentiation on
light microscopy, immunohistochemistry or electron microscopy. 1 Peripheral
Primitive neuroectodermal tumors occur outside the central and peripheral
central nervous system from cell rests derived from neural crest. 2 It is an
aggressive tumor of childhood and adolescence that rarely presents in orbit. 3
Very few cases have been reported in literature. 4-12
MATERIALS AND METHODS
Retrospective analysis of all cases of orbital PPNETs diagnosed between
1999 and 2008 at a tertiary care referral center in northern India was
undertaken. Demographic, clinical and imaging details of these cases
were studied. The haematoxylin and eosin sections, special stains and
immunohistochemistry of all cases were reviewed. Outcome after treatment
was studied where available.
RESULTS
Eleven cases of primary orbital PNETs were diagnosed at our center over a 10
year study period. The age of the patients ranged from 1.5 months to 20 years
(mean: 8.5 years). Duration of symptoms ranged from 10 days to 10 months. Eight
out of eleven cases presented with rapidly progressive painless proptosis and lid

69th AIOC Proceedings, Ahmedabad 2011
mass in 3 cases. Visual acuity on affected side varied from no perception of light
to 6/12.
Optic atrophy was seen in 1 case and exposure keratitis in one case. Significant
refractive error was seen in 9 cases. Computed tomographic scan of orbit
showed extra orbital extension in 6 cases with calcification in 5 cases. Lymph
node metastasis was present only in one case at diagnosis. Light microscopy
revealed a malignant round cell tumor in all cases which were confirmed by
a MIC2 positivity on immunohistochemistry. In one case electron microscopy
was done to confirm the diagnosis. Chemotherapy was given using vincristine,
doxorubicin, actinomycin-D and cyclophosphamide alternating with ifosfamide
and etoposide. Follow up after diagnosis was available only in 7 patients. Three
patients expired; two due to progressive disease and one due to chemotoxicity.
Four patients survived with complete disappearance of tumor at the end of
treatment. However globe could be salvaged in only two cases.
Discussion: The clinical, imaging and treatment details of previously reported
cases showed the median age to be 10 years with no sex predilection (mean:
10.5 years). The mean duration of symptoms at presentation was 3.3 months,
which is shorter as compared to 7.2 months in our series. Imaging findings in
PNET suggest presence of large, infiltrative, poorly circumscribed masses
with heterogeneous attenuation and variable contrast enhancement. They may
have areas of hemorrhage and necrosis, and sometimes cystic loculated areas. 13
Calcific densities are rare but were observed in three of our cases. The reported
rate of metastasis in PNET is approximately 20-25%. 14 No clear cut guidelines are
available for treatment of orbital PNET. Various combinations of chemotherapy,
surgery and radiotherapy have been used in the cases reported so far. To conclude,
PNET of orbit is a rarely reported entity. It is an aggressive tumor with scanty
literature and no set guidelines for treatment.
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