Path
Quiz Case 4:Case
history and images
Myxopapillary
ependymoma is a distinctive variant of ependymoma which was first
described as a separate pathological entity by Kernohan JW (Primary
tumours of the spinal cord and intradural filum terminale - Cytology and
cellular pathology of the nervous system. Vol 3 , 1932: 993-1025).
These tumours are usually restricted to the conus medullaris and filum terminale.
Extraspinal (soft tissue) myxopapillary ependymomas are rare tumours
which occur as direct extension into the soft tissue of the sacrococcygeal
area from a primary ependymoma of the spinal cord, cauda equina or filum
terminale. Alternatively these may occur as primary pre-sacral, pelvic or
abdominal tumours or as primary tumours of the skin and subcutaneous
tissue without direct connection to the spinal cord or filum terminale.
These tumours originate from extramedullary ependymal rests representing
remnants of the coccygeal medullary vestige , an ependyma lined cleft , and
is a derivative of the caudal neural tube persisting beneath the skin of
the postanal pit .
These slow growing tumours usually affect patients in the 3rd and 4th
decades and are slightly more common in males.
Clinically, this lesion is
often misdiagnosed as a pilonidal sinus or cyst. The differential
diagnosis also includes sacrococcygeal teratoma, neurogenic tumour, soft
tissue sarcoma and metastatic carcinoma. When the tumour involves sacrum
and coccyx , tumours such as chordoma and chondrosarcoma must also be
excluded.
Macroscopically the tumour usually presents as a well circumscribed,
encapsulated, ovoid mass. The cut surface has a greyish white, lobulated
appearance . In some cases cut surface shows mucoid areas, together with
areas of hemorrhage, calcification, fibrosis and cystic changes.
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Myxopapillary ependymoma has a distinctive appearance consisting of
cuboidal , columnar and spindle cells separated by basophilic mucinous
material and characteristic papillary arrangement around hyalinized blood
vessels.
Histologically the differential diagnosis includes
chordoma
and
schwannoma. Immunopositivity of the tumour cells with GFAP helps in
confirming the diagnosis of myxopapillary ependymoma.
These are indolent tumours and in most cases are completely curable
following total surgical resection. Following incomplete removal of the
tumour there is an increased risk of recurrence. The tumour has the
potential to metastasize to the lung, liver and lymph node. Prolonged post
operative follow up is necessary as late recurrences may occur several
years after the primary tumour is removed.
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