A 64-year progression of an intradiploic epidermoid of the frontal skull: illustrative case

Stefanie Ott Department of Neurosurgery, UKE Hamburg Eppendorf, Hamburg, Germany; and

Search for other papers by Stefanie Ott in
Current site
jns
Google Scholar
PubMed
Close
 MD
,
Andreas Lübke Center for Diagnostics, Institute of Pathology with the Sections Molecular Pathology and Cytopathology, UKE Hamburg Eppendorf, Hamburg, Germany

Search for other papers by Andreas Lübke in
Current site
jns
Google Scholar
PubMed
Close
 MD
,
Malte Mohme Department of Neurosurgery, UKE Hamburg Eppendorf, Hamburg, Germany; and

Search for other papers by Malte Mohme in
Current site
jns
Google Scholar
PubMed
Close
 MD
, and
Manfred Westphal Department of Neurosurgery, UKE Hamburg Eppendorf, Hamburg, Germany; and

Search for other papers by Manfred Westphal in
Current site
jns
Google Scholar
PubMed
Close
 MD
Open access

BACKGROUND

Epidermoid cyst tumors can arise as intradiploic tumors in the frontal skull bones around the fontanel in childhood but are mostly found at the frontal or frontotemporal base of the brain or in the cerebellopontine angle. Therefore, finding a symptomatic intradiploic lesion in the convexity in late adulthood is uncommon. Intradiploic epidermoids can cause complications as they grow, by eroding and perforating their surroundings, and in cases of destruction of the wall of a pneumatized sinus, they can cause pneumocephalus.

OBSERVATIONS

In the present case, a female patient presented with a skull lesion that had grown progressively over 64 years, resulting in spontaneous pneumocephalus. Surgery with subsequent cranioplasty was performed. The histological examination confirmed the presence of an intradiploic epidermoid.

LESSONS

This case highlights that complete resection of the lesion with subsequent cranioplasty is recommended before symptoms and reconstructive challenges due to the enormous size of the defect. This case serves as a reminder that intradiploic epidermoids, although uncommon, will expand throughout life and can cause significant complications such as pneumocephalus after decades. Timely surgical interventions after diagnosis are recommended to prevent further complications and to achieve a successful outcome in terms of complete resection and reconstruction.

ABBREVIATIONS

CSF = cerebrospinal fluid; MRI = magnetic resonance imaging

BACKGROUND

Epidermoid cyst tumors can arise as intradiploic tumors in the frontal skull bones around the fontanel in childhood but are mostly found at the frontal or frontotemporal base of the brain or in the cerebellopontine angle. Therefore, finding a symptomatic intradiploic lesion in the convexity in late adulthood is uncommon. Intradiploic epidermoids can cause complications as they grow, by eroding and perforating their surroundings, and in cases of destruction of the wall of a pneumatized sinus, they can cause pneumocephalus.

OBSERVATIONS

In the present case, a female patient presented with a skull lesion that had grown progressively over 64 years, resulting in spontaneous pneumocephalus. Surgery with subsequent cranioplasty was performed. The histological examination confirmed the presence of an intradiploic epidermoid.

LESSONS

This case highlights that complete resection of the lesion with subsequent cranioplasty is recommended before symptoms and reconstructive challenges due to the enormous size of the defect. This case serves as a reminder that intradiploic epidermoids, although uncommon, will expand throughout life and can cause significant complications such as pneumocephalus after decades. Timely surgical interventions after diagnosis are recommended to prevent further complications and to achieve a successful outcome in terms of complete resection and reconstruction.

ABBREVIATIONS

CSF = cerebrospinal fluid; MRI = magnetic resonance imaging

In this report, we describe the rare presentation of an intradiploic epidermoid cyst in a female patient. The lesion was initially discovered on radiography following a minor trauma at the age of 12 years. Over the course of several decades, the lesion showed progressive growth, particularly toward the intracranial compartment, and eventually became symptomatic, leading to the need for resection. Histological analysis confirmed an intradiploic epidermoid. Extensive erosion of the frontal skull base with destruction of the posterior wall of the frontal sinus led to pneumocephalus. This required subsequently extensive dural reconstruction. Cranial epidermoids are rare, mostly intradural lesions at the skull base. Although intradiploic manifestation is uncommon, these lesions should be noted as the differential diagnosis for any bony lesion of the skull.

Illustrative Case

A 76-year-old woman presented to our department with a painless swelling and visible deformity of her frontal skull. Although the lesion had been detected incidentally on radiography at a young age after a minor trauma, no further diagnostic evaluation had been performed. In 2016, the lesion was observed to have impressive dimensions on cranial magnetic resonance imaging (MRI), but it was still left under observation because it was asymptomatic. In 2022, however, the patient experienced episodes of spontaneous amnesia without additional focal neurological deficit, as well as retroorbital pain, prompting the repeat of cranial imaging. The imaging showed marked, asymptomatic displacement of the right frontal lobe, further growth, and the presence of spontaneous pneumocephalus. No signs of focal deficits or rhinoliquorrhea were detected. On physical examination, the lesion appeared as a painless swelling with well-defined borders and a bony consistency. Neurological and neurocognitive functions were normal, and the amnesic episodes were assumed to be unrelated. On subsequent MRI, the intradiploic epidermoid cyst demonstrated T2-weighted hyperintensity, inhomogeneous contrast enhancement, deformation of the frontal brain, and evidence of intracranial air (Fig. 1). On the basis of these findings, resection was recommended. Because of the unpredictable bone situation, which was later confirmed during the surgical procedure, we did not plan for a preformed skull implant to avoid the situation that it would not fit in the final opening. During surgery, the lesion appeared partly pasty and partly brittle with an off-white to brownish-yellow color. The frontal bone was, indeed, found to be partially thin, resembling an eggshell, but with a smooth surface from which the cyst wall could be removed (Fig. 2). The tabula interna was completely atrophic, assimilating to the dura. Given the patient’s age and the absence of neurological deficits, thin but solid parts of the intracranial cyst wall were left after removing the capsular membrane, providing attachment points for dural reconstruction. The perforation into the frontal sinus was exposed and sealed, and dural reconstruction was achieved with some pericranial flap material supplemented with Duragard (Integra) and was sealed with Tachosil (Takeda). The bone defect at the end of the removal was reconstructed with methyl methacrylate (Fig. 3). Postoperative imaging showed the resection cavity filled with air and cerebrospinal fluid (CSF). Subsequently, the brain expanded minimally, and the cavity filled with liquid, which was still hyperintense 3 months postoperatively because of some protein content, but was definitively sealed toward the subarachnoid space (Fig. 3). The patient had an uneventful recovery with no evidence of CSF leakage and is currently being followed up. Histological analysis of the resected tissue revealed lamellar bone with a cyst lined by stratified squamous epithelium, including a granular layer, and a content of abundant keratin flakes, consistent with an epidermoid cyst (Fig. 4).

FIG. 1
FIG. 1

Preoperative axial T2-weighted (A and B), contrast-enhanced (C), and fluid-attenuated inversion recovery (FLAIR) (D) MRI sequences.

FIG. 2
FIG. 2

Intraoperative appearance with bony defect of the tabula externa and interna and erosion of the dural layer.

FIG. 3
FIG. 3

Postoperative axial computed tomography (CT) (A and B) and contrast-enhanced MRI after complete resection (C–E).

FIG. 4
FIG. 4

Left: Cyst lined by stratified squamous epithelium. Right: Higher magnification reveals the granular layer. Hematoxylin and eosin, original magnification x50 (left) and x20 (right).

While cranial epidermoids in adults are mostly intradural at the base of the brain, this case highlights that a pediatric lesion of intradiploic manifestation will expand well into adulthood and present as bone lesions of the skull at an advanced age.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Cranial epidermoids account for approximately 1% of intracranial tumors, and only 25% of cranial epidermoids are located in the diploic skull.1 First described by Cushing in 1922, fewer than 300 cases have been published so far.2 Epidermoids have been named “pearly tumors,” as they consist of keratin, cellular debris, and cholesterol crystal shed from a stratified squamous epithelium with a slow linear growth rate due to progressive accumulation of the shed materials.3

Etiologically, they are thought to be of residual ectopic cells, as more or less all kinds of teratomas, originating from ectodermal remnants during neuroembryogenesis. Rarely, the origin is suspected to be a consequence of trauma due to the implantation of epithelial cells.3 Clinically, they present as slowly growing lesions, commonly located in the midline, intradurally and rarely intradiploically.1,4

Observations

This case highlights the long, basically asymptomatic course of a cranial epidermoid despite its potential size. However, continuous expansion can erode neighboring structures, potentially leading to complications such as meningitis and pneumocephalus. Nontraumatic pneumocephalus, indicated by symptoms such as retroorbital pain, can be a rare, first clinical presentation or an indication for treatment. When pneumocephalus is suspected, the erosive site should be carefully located and repaired intraoperatively to ensure adequate closure and to prevent recurrent pneumocephalus with resulting liquorrhea. The intradiploic location in this case is a rare feature, as cranial epidermoids are typically found intradurally. However, these lesions can still erode adjacent structures, such as the dural layer. Most patients with cranial epidermoids remain asymptomatic, but complications such as spontaneous rupture with chemical meningitis or pneumocephalus can occur, as shown in this case report.5 Although the dura had completely retreated at the highest pressure equator of our case, the patient did not report any episodes of meningitis-like spells, which are typical for spontaneous ruptures. Complete resection with removal of the epithelial cast wall can be achieved in up to 50%–80% of cases,3 although there is still ongoing debate about the role of complete resection. It is associated with a higher complication rate due to the adhesive intraoperative presentation, with possible morbidity.3 Incomplete resection is associated with a higher recurrence rate—namely, up to 24% of cases.6 Rarely, cranial epidermoids undergo malignant transformation.4

Lessons

Overall, this case serves as a reminder to consider cranial epidermoids in the differential diagnosis for intradiploic lesions, even in older patients. Intradiploic epidermoids are rare and more typical in pediatric patients, but if our patient had not been incidentally diagnosed at a young age and had chosen to ignore the finding for 64 years, the lesion would have been eventually diagnosed because of its progressive growth and subsequent pneumocephalus. Complete resection with cranioplasty should be aimed for, as it is possible and can help to prevent recurrence.

Author Contributions

Conception and design: Ott. Acquisition of data: Ott, Lübke, Westphal. Analysis and interpretation of data: Ott, Lübke, Mohme. Drafting of the article: Ott, Mohme. Critically revising the article: Ott, Mohme, Westphal. Reviewed submitted version of the manuscript: Ott, Mohme, Westphal. Approved the final version of the manuscript on behalf of all authors: Ott. Statistical analysis: Ott. Administrative/technical/material support: Ott. Study supervision: Westphal.

References

  • 1

    Chowdhury FH, Haque MR, Sarker MH. Intracranial epidermoid tumor; microneurosurgical management: an experience of 23 cases. Asian J Neurosurg. 2013;8(1):2128.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Krupp W, Heckert A, Holland H, Meixensberger J, Fritzsch D. Giant intradiploic epidermoid cyst with large osteolytic lesions of the skull: a case report. J Med Case Rep. 2012;6:85.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Ghartimagar D, Shrestha MK, Ghosh A. Recurrence of ruptured intracranial epidermoid cyst—a rare case report and presentation. Int J Surg Case Rep. 2020;76:310314.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Nagasawa DT, Choy W, Spasic M, et al. An analysis of intracranial epidermoid tumors with malignant transformation: treatment and outcomes. Clin Neurol Neurosurg. 2013;115(7):10711078.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Han GY, Won YS, et al. Intradiploic epidermoid cyst of the skull. J Korean Neurosurg Soc. 2005;38:6870.

  • 6

    Akar Z, Tanriover N, Tuzgen S, Kafadar AM, Kuday C. Surgical treatment of intracranial epidermoid tumors. Neurol Med Chir (Tokyo). 2003;43(6):275281.

  • Collapse
  • Expand
  • FIG. 1

    Preoperative axial T2-weighted (A and B), contrast-enhanced (C), and fluid-attenuated inversion recovery (FLAIR) (D) MRI sequences.

  • FIG. 2

    Intraoperative appearance with bony defect of the tabula externa and interna and erosion of the dural layer.

  • FIG. 3

    Postoperative axial computed tomography (CT) (A and B) and contrast-enhanced MRI after complete resection (C–E).

  • FIG. 4

    Left: Cyst lined by stratified squamous epithelium. Right: Higher magnification reveals the granular layer. Hematoxylin and eosin, original magnification x50 (left) and x20 (right).

  • 1

    Chowdhury FH, Haque MR, Sarker MH. Intracranial epidermoid tumor; microneurosurgical management: an experience of 23 cases. Asian J Neurosurg. 2013;8(1):2128.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Krupp W, Heckert A, Holland H, Meixensberger J, Fritzsch D. Giant intradiploic epidermoid cyst with large osteolytic lesions of the skull: a case report. J Med Case Rep. 2012;6:85.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Ghartimagar D, Shrestha MK, Ghosh A. Recurrence of ruptured intracranial epidermoid cyst—a rare case report and presentation. Int J Surg Case Rep. 2020;76:310314.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Nagasawa DT, Choy W, Spasic M, et al. An analysis of intracranial epidermoid tumors with malignant transformation: treatment and outcomes. Clin Neurol Neurosurg. 2013;115(7):10711078.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Han GY, Won YS, et al. Intradiploic epidermoid cyst of the skull. J Korean Neurosurg Soc. 2005;38:6870.

  • 6

    Akar Z, Tanriover N, Tuzgen S, Kafadar AM, Kuday C. Surgical treatment of intracranial epidermoid tumors. Neurol Med Chir (Tokyo). 2003;43(6):275281.

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 2231 2231 54
PDF Downloads 218 218 24
EPUB Downloads 0 0 0