Intraspinal Inclusion Tumor After Myelomeningocele Repair: A Long-Term Single-Center Experience

Histopathological presence of dermal elements in resected margins of neural structures obtained from initial repair surgery for myelomeningocele

Background

Development of dermoid or epidermoid cysts in myelomeningocele (MMC) sites is generally thought to occur in a delayed fashion due to implantation of dermal elements during initial repair surgery. Another theory is that dermal and dermoid elements may already be present within dysplastic neural structures at birth.

Methods

We experienced histopathological presence of dermal elements in resected tissues at initial repair surgery in four out of 18 cases with MMC who required resection of parts or margins of the neural structures to perform cord untethering. Since one of these cases has already been reported, we describe the clinicopathological findings for the remaining three cases.

Results

In Case1, cryptic dermoid elements were discovered in the terminal filum-like structure (FT-LS) caudal to the open neural placode (NP). The FT-LS had histopathological characteristics similar to the retained medullary cord. In Case 2, dermoid elements were discovered in the caudal margin of the dysplastic conus medullaris. In Case 3, a thin squamous epithelial layer overlapped the rostral margin of the NP where the NP was located near the skin. Case 1 developed an epidermoid cyst at 1 year and 2 months of age, which was totally resected.

Conclusion

Prenatally existing cryptic dermoid elements in the caudal portion of neural structures and remnants of dermal elements overlapping the rostral margin of the NP are associated with delayed occurrence of dermoid/ epidermoid cysts. Postoperative histopathological investigation of the resected specimens is recommended. Once dermal elements are revealed, repeated imaging examination and additional surgery should be considered.

Co-existent epidermoid and dermoid in a child with spinal dysraphism

Both spinal epidermoids and dermoids, given their common embryological origin, are referred as a single entity under the category of spinal inclusion tumors. Many theories, although speculative, have been proposed in relevance to their development. We present a unique case of dual pathology consisting of both epidermoid and dermoid components in a child with spinal dysraphism and succinctly touch upon the related embryological aspects and plausible pathogenesis. To the best of our knowledge, such co-existent entity has not been observed in the pediatric spine. The report adds to the gamut of the diverse observations of spinal dysraphic anomalies.

Ruptured dermoid cyst of the conus medullaris in the myelomeningocele sac revealed at the initial repair surgery

BACKGROUND

Dermoid cysts in the myelomeningocele (MMC) site are thought to arise in a delayed fashion because of iatrogenic implantation of dermoid elements at the time of the initial repair surgery. However, there have been few reports on dermoid elements already present at birth.

CLINICAL PRESENTATION

We report a patient, in whom dermoid cyst was located at dorsal aspect of the conus medullaris in the MMC sac. Between 23⁺³ and 24⁺⁴ weeks of gestation, rupture of the MMC sac occurred. At this time of gestation, we speculate that rupture of the dermoid cyst also occurred and dissemination of the cyst contents caused chemical arachnoiditis in the MMC sac. At the age of 1 day, surgery to repair MMC and postoperative histological findings revealed these rare pathologies.

CONCLUSION

Physicians should be aware of the possibility of rupture of a dermoid cyst in the MMC sac during fetal period.