DOI:10.2214/AJR.04.1718
AJR 2006; 186:1548-1550
© American Roentgen Ray Society
Abdominal Metastases of Medulloblastoma Related to a Ventriculoperitoneal Shunt
Ferdinando Loiacono1,
Aldo Morra2,
Silvia Venturini2 and
Luca Balestreri2
1 Dipartimento di Scienze Chirurgiche, Anestesiologiche e
Radiologiche—Università degli Studi di Ferrara, viale Giovecca
203, Ferrara, Italy.
2 Department of Radiology, Centro di Riferimento Oncologico-Aviano, Aviano,
Italy.
Received November 9, 2004;
accepted after revision March 7, 2005.
Address correspondence to F. Loiacono
(fer910{at}libero.it).
Keywords: cerebellum • MDCT • medulloblastoma • MRI
Introduction
We treated a 35-year-old woman 5 years ago for medulloblastoma. The
patient had a ventriculoperitoneal shunt and was admitted for intractable
constipation. A CT scan detected a huge abdominal mass, and a consequent
biopsy confirmed the metastatic nature of the lesion. We present the aspects
of peritoneal metastases from medulloblastoma and discuss the physiopathologic
mechanism of such rare localization.
Medulloblastoma is the most common brain tumor in children, representing
more than 20% of all pediatric brain neoplasms
[1,
2]. It usually affects boys
younger than 10 years old, and it is known for its malignancy
[3]. Medulloblastoma is much
less common in adults, accounting for less than 1% of all primary CNS tumors,
with an incidence peak between the ages of 30 and 40 years
[1]. The tendency to grow
within the cerebellum, especially in the vermis, may explain the shortness of
clinical symptoms, typically fewer than 3 months
[3]. The combined strategies of
surgery, radiotherapy, and chemotherapy have increased the 5-year survival
rate to approximately 50% [3].
Tumor recurrence and dissemination are still the crucial factors preventing
the cure. Neoplastic cells can be found in the CSF, and generally the site of
spread is by the spinal cord as a result of the natural flow of the liquid
from the posterior fossa. Extraneuraxial metastases are infrequent, and the
bone seems to be the preferred site because the neurosurgery allows neoplastic
cells access to the vascular system and peripheric spreading. The
ventriculoperitoneal shunt (VPS) device, inserted to avoid increasing
intracranial pressure often associated with the primary neoplasm, can be a
potential path of abdominal dissemination.
Case Report
We present a 35-year-old woman affected by a medulloblastoma. The
localization originally affected both the left cerebellum hemisphere and
tonsil. In November 1998, she underwent neurosurgery but the neoplasm could
only be partially removed, and a few weeks later she started adjuvant
chemotherapy. During the last chemotherapy cycle, the patient presented a
progressive worsening of the general condition caused by a tetraventricular
hydrocephalus treated with the insertion of the VPS with an Ommaya reservoir.
When the clinical conditions became acceptable, a new protocol of combined
chemotherapy was decided on together with intrathecal lumbar injection and
craniospinal radiation therapy. A brain and spine MRI performed at the end of
the complete therapy showed no sign of residual disease, whereas repeated CFS
cytologic examinations revealed persistent malignant cells. During the 3-year
follow-up, periodic brain and spine MRI scans did not reveal persistent or
recurrent disease and the VPS always appeared well positioned and functional.
In July 2003, the patient was admitted to our institution for intractable
constipation with diffuse abdominal pain. The CT scan revealed a large tumor
mass, 15 cm in diameter (Figs.
1A,
1B,
1C and
1D), expanding and almost
invading the complete pelvis, also involving the uterus and some proximal
intestinal loops. In the right upper abdomen, additional solid lesions 3 cm in
diameter were found with diffuse ascites. A CT-guided biopsy of the pelvic
mass confirmed the suspected diagnosis of metastatic medulloblastoma. Because
of worsening constipation, the patient underwent palliative lap-arotomy for
excision of the mass.
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Fig. 1D —35-year-old woman with medulloblastoma. Resected specimen shows
pelvic neoplasm occupying entire pelvis, dislocating intestinal loops and
uterus. Distal extremity of shunt is dipped within mass. Free fluid liquid is
also present.
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Discussion
VPS has been a well-established method, known for at least 100 years, that
is able to increase survival and improve quality of life in patients affected
by hydrocephalus. The modern devices, provided with a pressure valve, and,
more recently, with a Codman Hakim programmable valve, allow a noninvasive way
of controlling CSF drainage. Any location within lateral ventricles is
acceptable for the shunt implantation; however, the ideal positioning remains
near the foramen of Monro. Such devices, as with other types of CSF drainage
shunts, are subject to a long series of possible complications arising in
24-47% of cases [4,
5]. Shunt complications include
mechanical failures such as obstruction, disconnection, break, migration, and
leakage. Infections are also possible, not only within the CNS but also in the
peritoneal cavity, especially during the first 6 months after implantation.
The possibility of subdural hematomas or intraparenchymal and transtentorial
herniation must be considered when the symptoms are related to an intracranial
cause. Because the VPS is an artificial conduit of fluid communication between
the ventricular cavity and abdomen, it may also be an easy potential path of
metastatic dissemination. The latter occurs with malignant CNS neoplasms that
are not completely removed, especially germinomas and medulloblastomas, which
frequently spread through CSF
[6]. The case literature
reports, however, that the abdominal metastatic spread via VPS is rare, with
just 58 cases of abdominal metastases known from all types of primitive CNS
neoplasms in patients of all ages
[7]. To avoid abdominal
spreading of metastatic cells, the introduction of a Millipore filter at the
distal extremity of the drainage was suggested; however, this solution caused
frequent obstructions. The use of an experimental device capable of exposing
the draining CSF as it passes through a baffle system to a localized
high-intensity radiation field adequately shielded from surrounding healthy
tissue also had unsatisfactory results
[8]. Today, the only possible
solution appears to be a systemic chemotherapy protocol, as prophylaxis, and,
above all, sonography or CT surveillance of the abdomen as a part of the
routine follow-up of patients with a VPS implant.
References
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Introduction
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