Cranial lateral dermal sinus tract: illustrative case

Abstract

BACKGROUND

Dermal sinus tracts (DSTs) are rare congenital anomalies resulting from incomplete closure of the skin and neural tube. While most occur along the spinal midline, cranial DSTs are less common and typically found in midline occipital or nasofrontal regions. Lateral cranial DSTs, especially those involving the temporal bone, are extremely rare and poorly explained by current embryological models.

OBSERVATIONS

The authors conducted a scoping review identifying 19 publications describing 23 unique cases of lateral cranial DSTs. The patient in this exemplary case is a 20-month-old female who presented with a right temporal dimple identified at birth. MRI confirmed a deep DST extending to the bone without intracranial extension or infection. The patient experienced one episode of fluid drainage but was otherwise asymptomatic. Excision via craniectomy removed a 3.5-cm tract and associated dermoid cyst en bloc. Recovery was uneventful, and 5-month follow-up imaging showed no recurrence.

LESSONS

This case adds to the limited literature on lateral cranial DSTs and highlights that even benign dermoid cysts can enlarge and compromise adjacent neurovascular structures. Early excision remains crucial, and clinicals should consider atypical DST locations in infants with congenital skin dimples outside the midline.

https://thejns.org/doi/10.3171/CASE25745

Dermal sinus tracts (DSTs) are rare congenital lesions that create a persistent connection between the cutaneous ectoderm and underlying neural elements. They are a subtype of spinal dysraphism, a disruption in the neural tube.^1,2 Other subtypes of spinal dysraphism include myelomeningocele, lipomyelomeningocele, filum lipomas, and split cord formations.³ DSTs occur in approximately 1 in 2500 live births, with a slight male preponderance reported in the literature.^3,4

The most common clinical presentation of DSTs can include abnormal pigmentation, skin dimples, erythema, drainage of debris, and hemangiomas.^5–7 Patients with DSTs carry an increased risk of infection and irreversible neurological damage due to tethering, in which abnormal attachment of the spinal cord restricts its movement and leads to progressive injury of nervous system tissue,^3,8 potentially resulting in neurological deficits such as motor weakness, sensory disturbances, and/or gait abnormalities.⁷ As such, early prophylactic resection of DSTs is recommended to reduce these consequences, given the low surgical risk and low recurrence rate even after incomplete removal.^3,9 However, prior reports have demonstrated increased complications, such as delayed wound healing, associated with operating on DSTs prior to 6 months of age, leading many physicians to delay intervention until this time, regardless of age at diagnosis.³

DSTs that occur on the head are uncommon and are typically found in the occipital or nasofrontal regions.³ Those that occur on the lateral skull are even more rare, specifically those on the lateral frontotemporal region. Fewer than 25 total cases of DSTs involving the lateral temporal bone have been reported in the literature.^3,4 Furthermore, the lateral position is not explained by current pathophysiological theories, which primarily account for the midline DST variants. Here, we review the existing literature to explore clinical features, embryological mechanisms, and management strategies for this rare congenital lesion, and we present the unique case of a female patient with a lateral temporal bone DST and associated dermoid cyst recently managed at our center.

Illustrative Case

A 20-month-old female presented with a right cranial dimple first noticed at birth (Fig. 1). The patient was referred for neurosurgical evaluation due to concerns that the lesion could represent a DST. The parents reported no appreciable inflammation from the site of the dimple and denied any trauma to the region. However, the family noted scant leakage from the wound that began just prior to presentation. The patient had been meeting development milestones and was progressing well neurologically. There were no prior visits or diagnostic measures taken between birth and presentation at 20 months. The patient had a history of juvenile idiopathic arthritis and was found to have antinuclear antibodies. The patient underwent MRI to examine the patency and depth of the suspected tract (Fig. 2). This confirmed the diagnosis of a deep right temporal DST. There was no evidence of hydrocephalus, intracranial mass lesion, mass effect, or acute hemorrhage.

FIG. 1.

Initial presentation with a small right cranial dimple.

FIG. 2.

Preoperative MR images with the tract circled. A:Axial view showing part of the tract’s extension. B: Coronal view showing the external extension.

A surgical plan was established with no active concerns for intracranial infection or CSF leakage. The patient was placed in the supine position with the head turned to the left and slightly extended on a padded horseshoe head holder. A standard elliptical incision was made around the lesion, leaving the option for caudal extension as necessary, and the sinus tract was isolated with blunt dissection down to the bone defect.

A small craniectomy was performed to provide adequate exposure. An intradiploic dermoid cyst at the base of the tract was carefully elevated and excised en bloc. On excision, the tract and cyst were measured to be 3.5 cm long (Fig. 3). Residual tissue was meticulously removed to minimize the risk of recurrence. The dura remained intact. Despite the intradiploic location, the inner table of bone had been eroded away. Once meticulous dissection was complete and the lesion was felt to be removed in its entirety, the surgical field was irrigated with an antibiotic solution and closure commenced in an uneventful fashion. The patient was subsequently awakened and extubated without complications.

FIG. 3.

DST and cyst postexcision.

The patient returned to neurological baseline after surgery. The patient was discharged shortly thereafter. At the 1-month follow-up, the patient was reported to be well at home with no fever or neurological changes. The patient experienced delayed wound healing due to excessive irritation and scratching by the patient, although without infection or requirement for any subsequent treatment (Fig. 4). The patient remained well with excellent wound healing 6 months postoperatively without concern for recurrence.

FIG. 4.

Postoperative wound healing.

Literature Review Methods

We searched the PubMed database using the search strategy (“dermoid” or “dermal”) AND (“sinus tract” OR “Cyst”) AND ((“lateral” OR “temporal” OR “pterional” OR “laterotemporal” OR “temporolateral”), which yielded 367 publications. One publication was identified as a duplicate and removed. The 366 remaining nonduplicate publications were imported into Covidence for screening and were screened by two authors (J.M.C. and H.D.R.) by title and abstract for relevance. The 298 irrelevant studies were excluded. Publications were then read in full to determine inclusion eligibility. Publications reporting at least 1 case of a lateral and/or temporal DST were included. Publications were excluded if they did not include cranial or lateral DSTs (n = 5), were not obtainable in the English language (n = 7), did not include pediatric patients (< 18 years of age; n = 15), were not case reports (n = 12), or did not include sinus tracts (n = 10) (Fig. 5).

FIG. 5.

Literature review search strategy.

Ultimately, 19 publications were eligible for inclusion. Any disagreements during screening were resolved through a thorough discussion between two authors (J.M.C. and H.D.R.). Figure 5 summarizes the search strategy.

Results

Our literature review identified 23 cases of lateral cranial DSTs in 19 publications. The data collected included patient characteristics, clinical features about the presentation, sinus tract and cyst locations and size, and surgical information including technique, specialty, and complications (Supplemental Table 1). Of the 23 cases in the literature, 10 were male and 13 were female with a mean age of 2.7 years (range 2 months–10 years). All except 1 patient presented with skin findings including tissue swelling, discharge expressing from the sinus tract, and lesions.

Most DST skin findings were described as “temporal” or “frontotemporal” (21/23, 91.3%), with the others being described as “parietal” and “anterior ear.” However, the cyst location on the deep margin of the DST was widely variable between cases. Locations included bones (e.g., sphenoid and frontal bones), temporal fossa, middle ear, suture lines, and other intracranial sites. Surgical technique was widely variable between cases, with no clear determination made based on the location of skin findings and/or the deep marginal cyst. There were 2 cases each of DST recurrence, infection, transient neuropraxia, and postoperative discharge. One case had a postoperative residual cyst. The most severe complication was a postoperative cyst rupture. The most common specialties that performed these cases were plastic surgery, neurosurgery, otolaryngology, maxillofacial surgery, and oculoplastic surgery.

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Caused by disruptions in early neural development, DSTs can occur anywhere along the spinal cord. Although these congenital anomalies are rare, they most commonly present along the midline. However, paravertebral locations have been reported, and intracranial involvement is even less common.¹⁰ Lateral DSTs, particularly in the cranial region, are exceptionally rare, with fewer than 25 cases documented in the literature.^4,8

DSTs are most commonly diagnosed in children younger than 5 years of age and show no significant sex predilection. Diagnosis typically depends on when the patient develops symptoms or, in asymptomatic cases, when others notice the accompanying skin defect.¹¹ These lesions should be managed aggressively and should be completely resected in a timely manner after definitive diagnosis with imaging via CT or MR angiography.^3,11 Here, we reviewed the literature and reported a recent case at our center of a patient with a lateral cranial DST to better characterize the presentation, implications, and management of this condition.

Observations

Through our scoping review of 19 publications, we identified 23 previously reported cases of lateral cranial DSTs. Most presented with visible skin findings such as dimpling, swelling, or discharge typically in the temporal or frontotemporal region. However, despite the consistency in external appearance and location, the underlying tracts and associated cysts displayed significant variation in depth and anatomical destination. These ranged from cranial bones including the sphenoid and frontal bones to structures such as the middle ear and temporal fossa. This apparent disconnection between location of the skin findings and location of the covert deeper involvement presents a diagnostic challenge and emphasizes the need for high clinical suspicion of this condition, even in the absence of neurological symptoms.

In the present report, we highlight the case of a 20-month-old female with a temporal dimple that had been stable since birth. Initial imaging nearly missed the diagnosis due to its atypical location, which fell far lateral from midline. Ultimately, surgical exploration revealed a 3.5-cm sinus tract terminating in a dermoid cyst, which was excised en bloc via craniectomy without complication.

Our literature review demonstrates a clear consensus on the necessity for excision of lateral cranial DSTs. However, it also highlights a lack of uniformity in management strategies. Surgical approaches varied widely, depending on the depth and location of the tract and cyst. Importantly, preoperative imaging is essential to determine the full extent of the tract and whether a lesion exists at the base, which is critical for planning the surgical approach. Additionally, multiple surgical specialties including neurosurgery, plastic surgery, otolaryngology, and maxillofacial surgery were involved in cases in the literature, reflecting the multidisciplinary nature of these cases. While most patients had favorable outcomes, there were a few cases with reported complications, including infection, neuropraxia, postoperative discharge, residual cysts, and 1 case of a cyst rupture. These findings underscore the importance of early identification and complete excision to reduce the risk of recurrence and complications. During excision, the tract must be followed to its full depth and excised in its entirety. Blunt dissection is preferred, as it minimizes the risk of breaching the tract and allows sufficient dissection of any associated lesion at the base. However, the absence of a standardized surgical approach, likely due to both the rarity of these lesions and variability in presentation and pathogenesis, continues to pose challenges in their management.

The current understanding of embryological mechanisms of DSTs does not fully explain their rare development in non-midline cranial positions. Classic midline DSTs are attributed to disruptions in primary neurulation, when incomplete separation between the neuroectoderm and surface ectoderm results in a persistent stratified squamous epithelium-lined tract.¹² Some reports have extended this pathogenesis to explain lateral DSTs in the spinal or gluteal regions as a result of errors during secondary neurulation.^9,11 However, this explanation does not account for cranial DSTs that terminate laterally. Notably, none of the cases identified in our literature review provide a definitive embryological mechanism for lateral cranial DST formation. These observations highlight a significant gap in the current understanding of DST pathophysiology and the need for further investigations surrounding what may represent a distinct subtype of congenital anomaly.

Lessons

This case adds to the limited body of literature on lateral cranial DSTs and reinforces the importance of considering these lesions in the differential diagnosis of persistent and/or unusual facial skin findings in infants and children. Given the potential for growth, infection, and neurovascular destruction, timely surgical intervention remains the primary treatment. While recurrence is rare, our review identified one case from 1985 with inadequate preoperative imaging, and another with no clearly documented cause for recurrence. These underscore the importance of both thorough preoperative evaluation and meticulous resection. Notably, many publications of cases that did not recur emphasized complete resection of the tract and associated lesions. As such, to minimize the risk of recurrence, surgeons should aim to resect the entire tract and associated lesion at its base en bloc, ensuring complete removal and avoiding spilling of dermoid contents, which can increase the risk of regrowth. Additionally, surveillance imaging can be utilized on a case-by-case basis to aid in early detection of recurrence and guide long-term management.

A key limitation of our review is the inconsistency in localization terminology across published cases. While we focused on lateral cranial DSTs, different reports used varying descriptions such as “temporal,” “frontotemporal,” “parietal,” or “preauricular,” which may reflect overlapping, imprecise anatomical definitions in addition to potentially missing cases in our review. This heterogeneity complicates direct comparison and may lead to underestimation of true lesion prevalence in specific cranial regions.

Cranial DSTs are rare, and those occurring in the lateral temporal region are exceedingly uncommon. In our scoping review, we identified only 23 previously reported cases, most of which presented with temporal or frontotemporal skin findings but showed considerable variability in tract and cyst location, surgical approach, and outcomes. We present a unique case of a toddler with a lateral temporal DST, successfully managed with complete en bloc resection without recurrence or neurological complications. Although dermoid cysts are benign, they may enlarge over time and compromise adjacent neurovascular structures. Given the diagnostic challenges and potential complications, early recognition and surgical intervention remain the optimal strategy for management. This case adds to the limited body of literature on lateral cranial DSTs and highlights the need for clinical vigilance and continued reporting to further characterize the presentation, embryology, and treatment of these rare anomalies.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper

Author Contributions

Conception and design: JM Cohen, Kobets. Acquisition of data: JM Cohen, Reisert, E Cohen, Liriano, Kobets. Analysis and interpretation of data: JM Cohen, E Cohen, Kobets. Drafting the article: JM Cohen, E Cohen, Segal. Critically revising the article: all authors. Reviewed submitted version of manuscript: JM Cohen, Reisert, E Cohen, Segal, Bases, Kobets. Approved the final version of the manuscript on behalf of all authors: JM Cohen. Administrative/technical/material support: Liriano. Study supervision: Liriano, Kobets.

Supplemental Information

Previous Presentations

Previously presented at the International Society of Pediatric Neurosurgery Conference, Lyon, France, October 26–30, 2025; and the European Academy of Paediatric Societies, Lisbon, Portugal, October 18–20, 2025.

Online-Only Content

  Supplemental Table 1. https://thejns.org/doi/suppl/10.3171/CASE25745.

Correspondence

Joshua M. Cohen: Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY. joshua.cohen@einsteinmed.edu.