|LETTERS TO EDITOR
|Year : 2014 | Volume
| Issue : 2 | Page : 69
Orbital roof leptomeningeal cyst presenting as proptosis
Ishan Kumar, Ashish Verma
Department of Radiodiagnosis and Imaging, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
|Date of Web Publication||6-Feb-2015|
Departments of Radiodiagnosis and Imaging, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
|How to cite this article:|
Kumar I, Verma A. Orbital roof leptomeningeal cyst presenting as proptosis. Sudanese J Ophthalmol 2014;6:69
Leptomeningeal cyst or growing fracture is an uncommon entity, raising diagnostic dilemma, solved only by targeted imaging, in most cases. More importantly correct identification of the contents is the key to surgical planning and is the most important step to avoid inadvertent leptomeningeal and brain injury. In our experience of over 5000 cranial cross-sectional imaging studies, we came across an orbital roof leptomeningeal cyst presenting as proptosis, for the first time. Our esteemed ophthalmology colleagues would agree that their experience of this entity is even more limited, hence a short discussion of the issue would be worthwhile.
A 20-year-old male patient presented with swelling over left eyelid, proptosis and drooping of eyelid to the ophthalmology department of our institution. The patient gave a history of cranial trauma 12 years back which was initially thought to be irrelevant. No imaging details of previous trauma were present. Detailed ophthalmological examination was done on the patient that revealed a normal conjunctiva, cornea, pupil, iris, lens and the intraocular tension. The fundus examination did not reveal any abnormality. The lid swelling did not alter its shape or size with coughing or valsalva maneuver with no change on compressing external jugular vein. Suspecting the differential diagnosis of a mass lesion or orbital varix, computed tomography (CT) scan of orbits and brain was done. CT of the brain revealed an ill-defined area of hypodensity in left frontal lobe which was suggestive of encephalomalacic changes (black arrows in [Figure 1]a-c). A linear defect of maximum diameter 3.5 mm was noted in orbital plate frontal bone in the roof of the left orbit (black curved arrows in Figure 1b and c). Extrusion of meninges into orbit was noted through the defect containing fluid of cerebrospinal fluid attenuation (white arrow in [Figure 1]c). Imaging features suggested leptomeningeal cyst with growing skull base fracture.
|Figure 1: Contrast enhanced computed tomography scan of Brain and orbit. Axial (a), sagittal (b) and coronal (c) reconstructions showing a hypoattenuating nonenhancing area in brain (straight black arrow) representing an area of post traumatic encephalomalacia. A defect is seen in the floor of anterior cranial fossa/orbital roof (curved black arrow) through which the dura and cerebrospinal fluid (white arrow) re bulging into the orbit, representing the leptomeningeal cyst|
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Growing fractures are extremely rare after the age of 8 years. Main factor involved in the causation of growing fracture is laceration of the dura mater.  The encephalomalacic cyst adjacent to the fracture due to pulsatile forces of brain, herniate through the lacerated dura causing increased in size of the fracture. The intervening tissue prevents osteoblast migration and fracture healing. , Gradually, due to gravity the cyst herniate through the "growing" fracture along with its leptomeningeal lining and result into extracranially located cephaloceles or "leptomeningeal cyst". Growing fractures are relatively rare in well-supported skull base as it takes longer time and stronger herniating force for their development.  Rare location of the fracture in this case might account for its rare late presentation.
| References|| |
Khandelwal S, Sharma GL, Gopal S, Sakhi P. Growing skull fractures/leptomeningeal cyst. Indian J Radiol Imaging 2002;12:485-6.
Naim-Ur-Rahman, Jamjoom Z, Jamjoom A, Murshid WR. Growing skull fractures: Classification and management. Br J Neurosurg 1994;8:667-79.