Abstract
Dermoid cysts are one of the most common benign orbital tumours in children and usually occur unilaterally. Bilateral dermoid cysts in the orbit are rare. We report here, a case of bilateral orbital dermoid cysts, in a 29-month-old baby girl. The patient’s prognosis was favourable following surgical resection. Through this case report, we hope to increase the recognition and understanding of this condition.
Background
A periorbital dermoid cyst is an example of a congenital choristoma (i.e., a benign tumour consisting of histologically normal cells occurring in an abnormal location). 1 They are typically lined by keratinizing squamous epithelium and have adnexal structures such as hair follicles, sweat glands sebaceous glands, and even teeth.1,2 Dermoid cysts account for about 3–9% of all orbital masses. 3 They most frequently form in the superolateral region of the orbit near the frontozygomatic suture.3,4 Dermoid cysts are one of the most common orbital tumours in children, accounting for more than 40% of childhood orbital lesions and 89% of all orbital cystic lesions in childhood that require biopsy or surgical removal. 5 Unilateral dermoid cysts on the lateral end of one eyebrow are common but bilateral dermoid cysts are rare, and, to our knowledge, only two cases have been documented to date.6,7 To add to these reports, we describe here, a case of an infant with bilateral orbital dermoid cysts.
Case report
A 29-month-old baby girl presented to the Department of Orbital Disease and Ocular Oncology at our hospital with a two-month history of a mass at the eyebrow arch of both eyes. The child’s parents had observed that the baby had developed lateral bulges of the eyebrow arch on both eyes that were palpable masses. An orbital computed tomography (CT) scan showed bilateral orbital masses, which were recommended for surgical treatment, and so the infant was admitted to hospital.
The baby was healthy, had received vaccinations as planned, had no history of surgery or trauma, and had no family history of similar diseases. General physical examination showed no abnormalities. Ocular examination showed bilateral eyebrow arch lateral skin bulges, normal skin colour, palpable mass (approximately 10 mm × 10 mm), tough, no range of motion, no tenderness, and no abnormalities in the anterior and posterior segments of both eyes (Figure 1a–1c).
(a) Appearance of the child’s face showing the masses at the eyebrow arches of both eyes. (b) Appearance of the child’s face showing the mass at the eyebrow arch of the left eye and (c) Appearance of the child’s face showing the mass at the eyebrow arch of the right eye.
The orbital CT scan showed patchy low-density shadows in the upper outer part of the right orbit, with uniform density, approximately 10 mm × 6 mm in size (CT value approximately 0 Hounsfield units [HU]) and irregular patchy low-density shadows in the lateral wall of the left orbit, approximately 9 mm × 8 mm in size (CT value approximately -15 HU) (Figure 2). Magnetic resonance image (MRI) scans showed: nodular slightly hyperattenuation T1-weighted and slightly hyperattenuation T2-weighted signals approximately 9 mm in diameter under the integument of the right orbit (Figure 3a); mixed slightly hyperattenuation T1 and hypoattenuation T1 and slightly hyperattenuation T2 signals approximately 9 mm in diameter under the integument of the left orbit (Figure 3b); well-defined borders bilaterally, and a hypointense capsule (Figure 3c). On contrast enhanced scans, there was no significant enhancement in the lesion, and only mild enhancement of the capsule.
Computed tomography (CT) images of bilateral eyebrow masses. The orbital CT scan showed patchy low-density shadows in the upper outer part of the right orbit, with uniform density, approximately 10 mm × 6 mm in size (CT value approximately 0 Hounsfield units [HU]) and irregular patchy low-density shadows in the lateral wall of the left orbit, approximately 9 mm × 8 mm in size (CT value approximately -15 HU).
Magnetic resonance image (MRI) scans showed: nodular slightly hyperattenuation T1 and slightly hyperattenuation T2 signals approximately 9 mm in diameter under the integument of the right orbit (Figure 3a); mixed slightly hyperattenuation T1 and hypoattenuation T1 and slightly hyperattenuation T2 signals approximately 9 mm in diameter under the integument of the left orbit (Figure 3b); well-defined borders bilaterally, and a hypointense capsule (Figure 3c). On contrast enhanced scans, there was no significant enhancement in the lesion, and only mild enhancement of the capsule.
Clinical diagnosis was bilateral orbital cysts. After completing relevant preoperative examinations, the patient underwent bilateral orbital lesion resection under general anaesthesia two days after admission. During the surgery, lateral brow incisions were made and the tumours were exposed after subcutaneous tissue was separated layer by layer. The tumours were completely excised with intact capsules (Figure 4). The incisions were sutured layer by layer and healed well without any complications. The tumours were submitted for pathology. The patient received anti-inflammatory symptomatic treatment postoperatively. Pathological diagnosis confirmed that the two masses were dermoid cysts (Figure 5). The child recovered well and had no postoperative complications. She was discharged from hospital one week after surgery. At follow-up three months later, the skin incision had healed well without any obvious scaring or pitting deformity.
Excised cystic masses with intact capsules. The mass on the right side was larger than that on the left side.
Histopathological examination showing sebaceous glands in the cyst wall, stratified squamous epithelium (keratinization) in the cyst wall, and keratin in the cyst cavity (haematoxylin and eosin staining; magnification ×100).
The reporting of this study conforms to CARE guidelines. 8 Written informed consent was obtained from the patient’s parents/guardians to publish the patient’s anonymised data. The study was approved by the Research Ethics Committee of the Second Hospital of Jilin University (ethics review number is 2023–075).
Discussion
Dermoid cysts are one of the most common benign tumours of the orbit in children. 5 Most orbital dermoid cysts develop unilaterally and are rarely bilateral. As far as we are aware, only two cases of bilateral orbital dermoid cysts have been previously reported; one in USA and the other in Korea.6,7 This present report describes the first case of bilateral orbital dermoid cysts in a patient from China.
The orbital dermoid cyst is a benign mass composed of epithelial structures, dermoid appendages in the cyst wall, and keratinizing material and hair in the cyst cavity.1,2 CT scans show that orbital dermoid cysts are mostly located near the greater and lesser wing sutures of the sphenoid bone and the frontozygomatic suture; they are round, oval, or dumbbell-shaped, with well-defined borders and diverse cyst content density.3,4,9 MRI scans of the contents of the dermoid cysts show characteristic features; its fatty components are of high signal intensity on both T1-weighted and T2-weighted images, and fat-suppressed scans, excluding high signal intensity, show non-fatty components in the cyst wall and contents. 10 According to the number of fat-containing components, they can present as mottled, homogeneous with high signal intensity, or medium and low signal intensity. 5 In our case, the contents of the bilateral cysts were different, so although the pathology was the same as dermoid cysts, the CT values and MRI signals in the bilateral cysts differed.
Although orbital dermoid cysts are easily diagnosed due to the age of patient, their characteristic location and results from ocular, and imaging examination, bilateral facial masses are not commonly encountered and so may be missed. In addition, there is a slight natural protrusion at the eyebrow arch, so bilateral symmetrical dermoid cysts occurring in this region may not be immediately identified. In this present article, we report a rare case of bilateral dermoid cysts found in a 29-month-old baby girl. This report adds to the paucity of information about bilateral orbital dermoid cysts. Our aim is to provide further details about this condition assist clinicians in their recognition of this rare disease.
