Subcutaneous sacrococcygeal myxopapillary ependymoma misdiagnosed as pilonidal disease

When a dermatopathologist encounters the ultra-rare: A case series of superficial soft tissue/cutaneous myxopapillary ependymomas

Myxopapillary ependymoma (MPE) is an uncommon variant of ependymoma, almost exclusively seen in conus medullaris or filum terminale. MPE can be diagnostically challenging, especially when arising extra-axially. Here we report 5 cases of superficial soft tissue/cutaneous MPE, identified across three tertiary institutions. All patients were female and three of them (3/5, 60%) were children (median age 11 years, range 6-58 years). The tumors presented as slow-growing masses of the sacrococcygeal subcutaneous soft tissues, occasionally identified after minor trauma and clinically favored to be pilonidal sinuses. Imaging showed no neuraxis connection. Macroscopically, tumors were well-circumscribed, lobulated, and solid and microscopically they exhibited typical histopathology of MPE, at least focally. Two of the tumors (2/5, 40%) showed predominantly solid or trabecular architecture with greater cellular pleomorphism, scattered giant cells, and increased mitotic activity. All tumors (5/5, 100%) showed strong diffuse immunohistochemical expression of GFAP. One tumor clustered at the category "ependymoma, myxopapillary" by methylome analysis. Two patients (2/5, 40%) had local recurrence at 8 and 30 months after the initial surgery. No patients developed metastases during the follow-up period (median 60 months, range 6-116 months). Since a subset of extra-axial MPEs behaves more aggressively, timely and accurate diagnosis is of paramount importance.

Co-occurrence of subcutaneous myxopapillary ependymoma, dermal sinus tract, and filum terminale lipoma: a review of the pathobiology of caudal spinal cord development and spinal cord tethering. Illustrative case

BACKGROUND

Myxopapillary ependymoma (MPE) is typically benign and found in the conus medullaris and/or filum terminale, although rare cases of subcutaneous and extra-axial MPE have been reported. The co-occurrence of MPE, tethered cord syndrome (TCS) with lipoma of the filum terminale, and a dermal sinus tract is extremely rare, with only 6 reported cases in the literature. Here, the authors present the first case, to their knowledge, of an extra-axial, subcutaneous MPE co-presenting with TCS, lipoma of the filum terminale, and a dermal sinus tract and discuss the underlying pathobiology.

OBSERVATIONS

A 14-month-old male who presented for evaluation of a dermal sinus tract underwent magnetic resonance imaging, which revealed a tethered cord with associated lipoma. At 14 months, the patient underwent spinal cord detethering with resection of his sacral dimple and sinus tract. Histopathological evaluation revealed an incidentally found MPE within the dermal sinus tract.

LESSONS

The authors review the underlying biology of MPEs, tethered cord syndrome, and dermal sinus tracts, and explore possible points of convergence within the developmental pathways that may result in this unique concomitant presentation. Additionally, they suggest that extra-axial MPE may be underappreciated and underdiagnosed; this case suggests that extra-axial MPE may be only effectively diagnosed with histological studies.

Subcutaneous Sacro Coccygeal Myxopapillary Ependymoma: A Case Report and a Comprehensive Review of the Literature Reappraising Its Current Diagnostic Approach and Management

Sacrococcygeal myxopapillary ependymoma (MPE) is an uncommon type I glial tumor detected most frequently in the lumbosacral area of adolescents and children. It is usually presented as an intradural ependymal tumor that originates from the filum terminale and other locations within the ventricular system along the craniospinal axis. In rare cases, however, MPE may develop as a primary subcutaneous tumor in the sacrococcygeal area. Tumors can also appear as a dorsal sacrococcygeal growth or subcutaneous nodule. In this case report, we describe a rare case presenting as a subcutaneous sacrococcygeal mass in an elderly female that was subsequently resected and confirmed as subcutaneous MPE. The current standard treatment for MPE is maximal surgical resection with or without postoperative radiotherapy based on the locoregional extent and histological grading. However, there is limited evidence that radiotherapy for oligometastatic foci improves longevity or extends the time to recurrence. In addition to this case report, we provide a comprehensive review of similar cases and case series in the medical literature. Prospective studies evaluating the efficacy of resection and/or radiotherapy are required for improved management of extradural MPE.

Surgical management of a rare myxopapillary ependymoma of the gluteal region: A case report

Background:

Ependymomas are rare tumors originating from neuroepithelial cells lining the wall of the ventricles or central canal of the spinal cord. While these tumors mainly occur within the central nervous system (CNS), there are occasional reports in children and young adult patients with a primary tumor occurrence outside of the CNS. Ependymomas of the sacrococcygeal region have been infrequently described in the literature with no standard of care established. We present a case report and review of the literature regarding this rare entity.

Case Description:

A 24-year-old woman presented with right gluteal pain worsened by sitting and a palpable soft tissue mass of the sacrococcygeal region. Magnetic resonance imaging revealed a 3.7 cm cystic mass centered in the right gluteal region. She underwent a biopsy at an outside institution, with histology revealing myxopapillary ependymoma. The patient was referred to our hospital and underwent an interdisciplinary neurosurgical and orthopedic oncology en bloc resection of the ependymoma, which intraoperatively appeared to originate from the coccygeal nerve.

Conclusion:

In the present report, the authors demonstrate that a myxopapillary ependymoma may present as an isolated gluteal mass attached to the coccygeal nerve, without frank CNS involvement. Furthermore, an interdisciplinary approach to surgical resection of this lesion appears to represent an effective treatment modality.