CASE 1781 Published on 31.03.2006

Dermoid of the orbit

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Cakirer S

Patient

34 years, female

Categories
No Area of Interest ; Imaging Technique CT, MR, MR
Clinical History
A 34-year-old female patient was referred to the MRI unit with a left-sided orbital mass that revealed slow growth over the previous 2 years. The mass was soft, and was not adherent to the cutaneous and subcutaneous tissue of the periorbital region. It also caused lobulation of the neighbouring skin.
Imaging Findings
The patient was referred to the MRI unit with a left-sided orbital mass that revealed slow growth over the previous 2 years. The mass was soft, and was not adherent to the cutaneous and subcutaneous tissue of the periorbital region. It also caused lobulation of the neighbouring skin. Following axial CT scanning of the orbits, T1-weighted spin-echo, T2-weighted fast spin echo, and T1- and T2-weighted fat-suppressed images of the bilateral orbits were obtained on three planes with 3-mm slice thickness on a 1.5T MR scanner. CT images showed a well-delineated soft tissue mass with fat density, located at the temporal side of the left orbit extraconally just beneath the orbital wall. The mass extended towards the cutaneous tissue anteriorly and laterally as well. MRI images revealed the homogeneous high signal intensity of the mass on all sequences with a total loss of signal on fat-suppressed sequences. The mass was surgically resected with a histological diagnosis of orbital dermoid.
Discussion
Orbital dermoid is a well-circumscribed cystic lesion with a thick capsule. It is the most common benign orbital tumour of the paediatric age group. Dermoids develop secondary to the inclusion of ectodermal elements during the closure of the anterior neuropore of the neural tube. In hisopathological studies dermoids are seen to contain dermal structures, including sebaceous glands and hair follicles, as well as blood vessels, fat, and collagen, within a fibrous capsule. Dermoids most commonly present with a non-tender mass at the superolateral orbital rim. They have very slow growth, and are usually dormant for years. They are most commonly located either superolaterally (60%) or superomedially (25%) between the globe and the orbital periosteum. The lesion reveals fat density (-50HU to -80HU) with a well-defined capsule on CT imaging. It may rarely contain punctate calcifications. It is hyperintense on all classical MRI sequences, and does not enhance following IV gadolinium contrast administration. Expansion or pressure erosion of the bony orbit may be associated in rare cases. Surgical resection is curative, and most of the lesions are resected for cosmetic purposes.
Differential Diagnosis List
Dermoid of the orbit.
Final Diagnosis
Dermoid of the orbit.
Case information
URL: https://eurorad.org/case/1781
DOI: 10.1594/EURORAD/CASE.1781
ISSN: 1563-4086