Key-words:
Malignant peripheral nerve sheath tumors - neurofibromatosis type 1 - prognosis -
survival
Introduction
Malignant peripheral nerve sheath tumors (MPNST) typically originate from nerves of
the extremities and trunk or from preexisting neurofibromas. The occurrence of MPNST
tumors within the neuroaxis is uncommon. Even rarer is the finding within brain parenchyma.
Treating it is still a challenge. Here we presented a patient with MPNST and the suggested
treatment, either to treat or not.
Case Report
A 23-year-old female was admitted to our hospital with a 1-month history of the right
temporal swelling associated with intermittent headache, loss of appetite, and loss
of weight, which is progressively worsening. She had a strong family history of neurofibromatosis
type 1 (NF1) and one of her siblings passed away due to brain tumor. Clinically, there
was a mass at her right scalp measuring 5 cm × 5 cm, which was firm and tender on
palpation.
Computed tomography (CT) brain showed an enhancing extra-axial lesion at the right
temporoparietal region with bony erosion [[Figure 1]] and [[Figure 2]]. We have proceeded with right craniotomy and excision of tumor. Histopathological
examination results came back suggestive of malignant peripheral malignant nerve sheath
tumor with immunohistochemical stain showing that the cells are only positive to vimentin
and CD56, while Ki-67 is more than 50%. Thorax-abdominal-pelvic CT was done for surveillance
and a synchronous retroperitoneal mass was noted with intraspinal extension and metastatic
bony lesion to the right acetabulum [[Figure 3]]. Hence, magnetic resonance imaging spine was proceeded which revealed tumor deposits
at the retroperitoneal and upper lumbar spine involving the L1 vertebral body and
epidural extension was noted from T12 to L1 and bilateral L1/L2 foramina as well.
However, no surgery was done in view of advance progression of the disease. Instead,
she was referred to oncology team.
Figure 1: Computed tomography brain showing soft tissue view. An enhancing lesion measuring
7 cm x 7 cm
Figure 2: Computed tomography brain showing bone view bony erosion by the underlying lesion
Figure 3: Thorax-abdominal-pelvic computed tomography showing retroperitoneal mass with intraspinal
extension
She had completed 4 cycles of palliative chemotherapy and 10 cycles of radiotherapy
before coming again after 5 months completion of treatment with a new complaint of
left-sided chest wall swelling with shortness of breath. On examination, there was
a mass fixed on the left chest wall, which was firm and measuring 5 cm × 5 cm. Chest
X-ray revealed mass at the left lower zone eroding the ribs with ipsilateral pleural
effusion causing tracheal deviation. Therefore, she was then referred to palliative
care unit.
Discussion
A malignant peripheral nerve sheath tumor (MPNST) is a tumor that develops in the
protective lining that covers nerves. The first symptom of MPNST is often a lump or
mass that increases in size, sometimes causing pain or a tingling sensation. Treatment
of MPNST begins with surgery to remove as much of the tumor as possible and may or
may not followed by radiation therapy to decrease the chance of a recurrence. Chemotherapy
might be used if the whole tumor cannot be removed during surgery or to treat a metastasis.[[1]],[[2]]
These tumors account for up to 10% of all soft tissue sarcomas [[3]] and are associated with poor prognosis unless wide excision of the tumor is undertaken
before local invasion or distant metastasis can occur. The incidence of sporadic MPNST
is low, with a lifetime risk of 0.001%,[[4]],[[5]] but in association with the familial condition NF1, where these tumors often arise
from malignant transformation of a plexiform neurofibroma, the incidence is much higher.
Evans et al.[[6]] estimated the lifetime risk of developing MPNST in the population of patients with
NF1 to be as high as 13%.
Due to the relative rarity of MPNST, there have been few large studies into survival.
The chance of surviving a diagnosis of MPNST depends on the size and location of the
tumor; people who have a small tumor tend to survive longer than those with a large
tumor, and people with a tumor in the arms or legs tend to survive longer than those
with a tumor in the head-and-neck regions.[[5]],[[7]] Furthermore, MPNSTs that are treated when they first occur have a better prognosis
than when the tumor has regrown after initial treatments or spread to distant parts
of the body.[[7]]
One study of 140 patients found that 26% of individuals diagnosed with MPNST were
living 10 years after the initial diagnosis.[[8]] Of those patients who developed a metastasis, 8% were living 10 years after the
initial diagnosis.[[8]] Other than that, large tumor size at presentation (typically >5 cm) has been the
most consistently determined adverse prognostic factor across all series.[[8]],[[9]],[[10]]
Meanwhile, several studies showed relation between prognosis and NF1 factor. MPNST
patient with NF1 related showed worst prognosis compared to sporadic MPNST patient.[[11]] There has been some evidence that poor prognosis is also reflected by an increased
proliferation index of Ki-67 as measured by immunohistochemical analysis, and a number
of studies have identified Ki-67 as an independent prognostic factor.[[12]],[[13]]
To summarize, the patient presented with tumor size >5 cm, tumor location at the head
or neck, strong family history of NF1, recurrent or distant metastatic, and increase
Ki-67 has poor prognosis.
Conclusion
Based on our illustrated case, our patient presented with brain lesion which its size
was more than 5 cm, the patient had significant family history of NF1, presence of
distant metastases, and head-and-neck region as its location and immunohistochemical
analysis showed Ki-67 of more than 50%. This is in tally with our aforementioned literature
reviews which correlate these peculiar features with poor prognosis. This can indeed
be appreciated when our patient came back with new symptoms in Declaration of patient
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