Published ahead of print on January 9, 2008
doi: 10.3174/ajnr.A0924
American Journal of Neuroradiology 29:434-435, March 2008
© 2008 American Society of Neuroradiology
Case Report
PEDIATRICS
Malignant Transformation of a Lipomyelocele into a Rhabdomyosarcoma?
A.M. O'Connella,
D. Allcuttb,
F. Brettc and
S. Ryana
a Department of Radiology, Children's University Hospital, Dublin, Ireland
b Department of Neurosurgery, Beaumont Hospital, Dublin, Ireland
c Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
Please address correspondence to AnnaMarie O'Connell, MD, Department of Radiology, Children's University Hospital, Temple St, Dublin, Ireland; e-mail: amoconnell{at}yahoo.com
SUMMARY: We report the unusual transformation of a lipomyelocele
to a rhabdomyosarcoma in a 3-year-old boy. A lipomyelocele is
not considered pre-malignant, but the possibility of developing
such a tumor may represent another reason for close neurological
follow-up in patients with spinal dysraphism.
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Introduction
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Alipomyelocele is an intraspinal lipoma that is tightly attached
to the dorsal surface of an open spinal cord.
1 The spinal cord
remains within the spinal canal unlike a lipomyelomeningocele,
in which the thecal sac herniates through the spina bifida.
Lipomyeloceles are associated with tethering of the cord but
not with malignancy.
2
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Case Report
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A spinal sonography was performed on the first day of life in
a full-term neonate with a complex hemangioma over the sacrum
(
Fig 1). This showed the spinal cord ending in a sacral lipoma.
The diagnosis of a lipomyelocele was confirmed by MR imaging
at 3 months of age (
Fig 2). The baby was managed conservatively
with frequent neurosurgical assessment. At 3 years of age, he
presented with an unwillingness to walk and general malaise.
He had developed a large sacral bulge with a superimposed hematoma.
Spinal MR imaging demonstrated a new large mass arising from
the lipoma and distal spinal cord within the sacral canal (
Fig 3A).
There was surface enhancement of the cord (
Fig 3B) and brain
stem (
Fig 3C) consistent with meningeal seeding of the tumor.
These findings were confirmed at surgery, and pathologic examination
of the partly excised tumor revealed a rhabdomyosarcoma. Histology
showed a pleomorphic malignant spindle cell tumor (
Fig 4) positive
for muscle markers.
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Fig 2. Sagittal T1-weighted MR image obtained at 3 months confirms the sonographic finding of the tethered spinal cord (arrowhead) ending in a lipomyelocele (arrow).
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Fig 3. A, Sagittal T1-weighted MR image at 3 years shows a new large homogeneous mass of low signal intensity (arrow), apparently arising from the lipomyelocele and distal spinal cord within the spinal canal. B, Postcontrast T1-weighted sagittal MR image shows multiple foci (arrowheads) of high signal intensity in the distal thoracic and lumbar spinal cord consistent with metastatic seeding. C, Sagittal postcontrast T1-weighted MR image demonstrates multiple foci (arrowheads) of high signal intensity in the brain stem and cervical and upper thoracic spinal cord, consistent with metastatic seeding.
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Fig 4. Resection of this sacral mass revealed a pleomorphic malignant spindle cell tumor at pathology, consistent with a rhabdomyosarcoma (hematoxylin-eosin).
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Discussion
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The clinical finding of sacrococcygeal cutaneous stigmata, such
as that seen in this baby, has been clearly linked with occult
spinal dysraphism. Screening spinal sonography is indicated
in these babies, and positive findings can be confirmed by MR
imaging. Management is usually conservative. Follow-up assessments
are focused on the detection of any possible evidence of neurologic
complications of the tethered cord and, in particular, of any
sign of neurologic deterioration. Such findings may be indications
for surgical untethering of the cord and resection of the lipoma.
The possibility of development of tumors in neural tube defects has been described.3–6 Lipomyeloceles are not, however, considered premalignant conditions. To our knowledge, the development of a rhabdomyosarcoma within a lipomyelocele has not been previously described. It has, however, been described originating from the central nervous system (CNS). There are no skeletal muscle cells in a lipomyelocele, but it is tightly attached to the dorsal aspect of the open spinal cord.
Primary intracranial rhabdomyosarcoma is a rare tumor in infancy and childhood, which is found in various locations in the CNS.7 The clinical course worsens rapidly, and the final outcome is poor, with a median survival time of 8–10 months.7 Invasion of the meninges, spontaneous intratumoral bleeding, spinal leptomeningeal CSF spreading of tumor cells, and early recurrence of the mass are the distinctive features of rhabdomyosarcoma.7
Intracranial rhabdomyosarcoma has also been described in association with subdural hematoma. The authors propose the possibility of sarcoma development secondary to chronic inflammation and proliferation in subdural collection.8 The coexistence in this instance seems coincidental, however, and subdural hematoma was known to be secondary to a fall.
The development of a rhabdomyosarcoma in this case report is likely embryonal. Although originating from a benign lesion such as a lipomyelocele has not been described previously, to our knowledge, unlike CNS origin, it may represent a very rare transformation.
The possibility of development of such a tumor, however rare, presents another reason for close neurologic follow-up of children with spinal dysraphism. It emphasizes the importance of early neuroimaging of the spinal canal when any new neurologic signs or symptoms develop.
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References
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- Unsinn KM, Geley T, Freund MC, et al. US of the spinal cord in newborns: spectrum of normal findings, variants, congenital anomalies, and acquired diseases. Radiographics 2000;20:923–38[Abstract/Free Full Text]
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- Thorp RH. Carcinoma associated with myelomeningocele: case report. J Neurosurg 1967;27:446–48[Medline]
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- Nejat F, Keshavarzi S, Kalaghchi B, et al. Chronic subdural hematoma associated with subdural rhabdomyosarcoma: case report. Neurosurgery 2007;60:E774–75, discussion E775[Medline]
Received October 27, 2007;
accepted after revision October 31, 2007.
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