Case 2
An 18 years old female, with no addictions or comorbidities, developed
an episode of seizure in 2016. Without adequate workup, she was started
on phenytoin. The seizures recurred in 2018, while she was on the same
anti-epileptic drug. MRI brain done in August 2016 showed a well-defined
solid cystic lesion measuring 48x37x46 mm in right parieto-occipital
region, with heterogeneous post-contrast enhancement in solid component.
Mass effect was seen in form of effacement of adjacent sulci and
compression of ipsilateral lateral ventricle. She then underwent surgery
with excision of right parieto-occipital lesion, with the post-operative
HPR favoring a diagnosis of a peripheral PNET. She was advised to
undergo RT, but she never received RT due to some personal reasons, nor
did she receive any systemic therapy. She remained asymptomatic for the
next five years.
In April 2023, she developed pain in nape of neck, along with vomiting
episodes, left sided upper and lower limb weakness. CT scan of brain
revealed a heterogeneous space occupying lesion (SOL), measuring 68x49
mm in right parieto-occipital region, with areas of bleed and complex
cystic component. Mass effect was seen in form of compression of third
and right lateral ventricles and displacement of left lateral ventricle.
She underwent surgical resection for the recurrence in September 2023.
The HPR showed different diagnosis at three different centres, namely,
- embryonal tumor with multilayered rosettes or CNS tumor with BCOR
duplication,
- WHO grade 2 ependymoma
- high grade neoplasm with divergent differentiation.
After surgery, the patient presented to us in February 2024, without
having received any adjuvant therapy even this time. Our in-house slide
and block review revealed PNET with PanCK, NKX2.2 and EMA positivity,
while GFAP, OLIG 2, CK7 and CK20 were negative. MRI brain shown inFigure 6 , revealed a heterogeneously enhancing solid cystic
mass in the right parieto-occipital region, measuring 8.3 x 5 x 7.3 cm,
underneath the craniotomy site, suggestive of disease recurrence for the
second time. Also, a 9.2 x 9.2 mm well-defined enhancing lesion of
similar morphology was seen in the right occipital lobe, likely a
metastatic deposit. Mass effect was seen as a 6 mm midline shift to
left. MR spectroscopy shows absolute choline peak with Choline to
N-Acetyl Aspartate ratio 1.7. MR perfusion shows hyper perfusion with
relative cerebral blood volume being 1.6. Whole body PET-CT was done to
rule out any extracranial source of intracranial PNET, but there was no
metabolically active disease noted elsewhere. CSF cytology was also
negative.
She underwent Re-do right parieto-occipital craniotomy and near total
tumor excision in last week of May 2024. The small occipital lesion
could not be tracked with USG and was left behind. Post-operative MRI
brain showed stable well-defined enhancing lesion involving the right
occipital lobe, with expected postoperative changes in right parietal
lobe, as shown in Figure 7 . The postoperative HPR showed a
tumor arranged in trabeculae, cords, nests, tubules and rosette pattern,
with extensive sclerosis, as shown in Figure 8 . It was composed
of round to elongated cells with moderate nuclear pleomorphism and clear
cytoplasm. A diagnosis of PNET was made again, with diffuse PanCK, focal
EMA, strong complete membranous CD99, NKX2.2 and FLI-1 positivity, and
negative staining for GFAP, INSM-1 and synaptophysin. EWSR1 gene
rearrangement tested with FISH showed split signals and/or loss of green
signals only in 8% tumour cell nuclei, and again it was classified as
Embryonal tumour as per WHO CNS Tumour classification 2021 and treatment
was decided upon as per High-risk MB protocol. She has been planned for
CSI to a dose of 36 Gy in 20 fractions, 1.8 Gy per fraction, followed by
radiotherapy boost to residual disease and tumour bed to a dose of 18 Gy
in 10 daily fractions, 1.8 Gy per fraction by VMAT technique. The
concurrent chemotherapy planned is daily vincristine, 1.5
mg/m2, followed by adjuvant chemotherapy as per
Packers A regimen.