Congenital intradiploic arachnoid cyst presenting as painless proptosis Reecha Sachdeva, MD,a Mary E. Turell, MD,a Steven R. Meadows, MD,b Todd M. Emch, MD,c and Arun D. Singh, MDa
A 12-year-old girl presented with several years of progressive painless proptosis and orbital fullness. On imaging, she was found to have marked expansion and remodeling centered in the right greater wing of the sphenoid bone with an adjacent middle cranial fossa arachnoid cyst. A clinical diagnosis of intradiploic arachnoid cyst was made. This entity was benign, and other ophthalmic and neurologic signs or symptoms were absent. Our patient was observed without surgical intervention. To our knowledge, this is the first such case reported in a child. Although this cyst has been described in the occipital and frontal bones, this is the first description of occurrence in the sphenoid bone. FIG 1. External chin-up photograph demonstrates gross axial proptosis of the right eye. The eye otherwise appears normal.
Case Report
A
12-year-old girl was referred for evaluation of right-sided orbital fullness. Her ocular history was remarkable for refractive error ( 3.00 D spherical correction in both eyes) and soft contact lens wear. Her medical history was unremarkable, she had no history of trauma, and family history was noncontributory. She had presented to her local ophthalmologist for a general eye examination and contact lens fitting and mentioned that her right eye had “seemed larger” for the past year, but she had no associated ocular complaints of pain, decreased vision, or diplopia. On examination, best-corrected visual acuity was 20/20 in each eye. She had gross prominence of the right orbit with fullness of the right brow and superotemporal orbital rim. Hertel exophthalmometry revealed 4 mm of right axial proptosis (Figure 1). Ocular motility was full and alignment was orthophoric. Anterior segment and dilated fundus examination were unremarkable. Specifically, the optic disk had no evidence of swelling or atrophy. Humphrey visual fields were also normal. Computed tomography imaging of the orbits without contrast confirmed right proptosis and demonstrated marked osseous expansion and remodeling centered in
Author affiliations: aCole Eye Insitute, Cleveland Clinic, Cleveland, Ohio; bFairview Eye Center, Cleveland, Ohio; and cDivision of Neuroradiology, Imaging Institute, Cleveland Clinic, Cleveland, Ohio Submitted June 2, 2011. Revision accepted July 13, 2011. Correspondence: Arun D. Singh, MD, Cole Eye Institute, Cleveland Clinic, 9500 Euclid Ave. Desk i30, Cleveland, OH 44195 (email:
[email protected]). J AAPOS 2011;15:601-603. Copyright Ó 2011 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 doi:10.1016/j.jaapos.2011.07.013
Journal of AAPOS
the greater wing of sphenoid bone (Figure 2A). The area of expansion measured 4.5 cm anteroposterior by 2.2 cm transverse by 4.0 cm craniocaudal and resulted in anterior deviation and bowing of the right posterior orbital wall. Subsequent magnetic resonance imaging further characterized the lesion as following cerebrospinal fluid (CSF) signal intensity on all pulse sequences, and it better visualized an underlying right middle cranial fossa arachnoid cyst (Figure 2B). There was no enhancement and no solid component of the mass. Aside from the minimal mass effect from the right posterior orbital wall remodeling, both orbits, as well as the remaining brain parenchyma, were normal. A presumptive clinical diagnosis of intradiploic arachnoid cyst was made on the basis of the imaging characteristics of the lesion as well as the presence of the immediately adjacent right middle cranial fossa arachnoid cyst. The intradiploic extension likely occurred through a defect in the dura adjacent to the arachnoid cyst. Old photographs of the patient identified the presence of progressive right brow fullness dating back 5 years before presentation (e-Supplement 1, available at jaapos.org). Given the benign nature of this lesion, with slow growth over several years, its minimal deformity, and its absence of ocular and neurologic symptoms, we decided to observe this lesion with serial examinations and imaging 6 months after its initial presentation. The case was additionally reviewed in detail at the tumor board meeting at the Cleveland Clinic, with input from the Neuroradiology, Neurosurgery, Oncology, and Radiation Oncology services. This multidisciplinary team was in agreement with the plan. Specifically, the neurosurgery service postulated that surgical intervention in this setting could likely create a neurologic deficit, temporalis muscle atrophy, or other complications.
601
602
Sachdeva et al
Volume 15 Number 6 / December 2011
FIG 2. A, Axial noncontrast computed tomographic image demonstrates marked expansion and remodeling centered in the greater wing of the sphenoid. There is also an immediately adjacent arachnoid cyst overlying the right temporal lobe. B, Axial T2-weighted image confirms the presence of a middle cranial fossa arachnoid cyst and demonstrates fluid signal intensity in the cyst similar to that within the remodeled and expanded greater wing of sphenoid.
Discussion Arachnoid cysts are congenital outpouchings within the arachnoid membrane filled with CSF. Occasionally, these cysts occur in the intracranial intradiploic space, the majority of which have been reported after head trauma and have been associated with posttraumatic skull fractures in children. Although most intradiploic arachnoid cysts described in the literature have been traumatic in origin, there have been several reported nontraumatic cases.1-9 These nontraumatic cystic lesions are presumed to be congenital, with CSF pulsating through a dural defect into the intradiploic space and leading to gradual enlargement with thinning of the inner and outer tables of bone.1 Given the low pressure of CSF pulsations, Thomas and Rout1 speculated that the lesions must be initiated before ossification of the cranium because normal CSF pressure would not likely cause intradiploic expansion in otherwise intact bone. Although these nontraumatic cases are presumed to be congenital, these cysts are generally identified in older patients. In the 15 cases identified in the literature (e-Supplement 2, available at jaapos.org),1-9 the average age was 60 years (range, 25 74 years), and all but 2 patients were older than 50 years of age.1,7 Of the 15 cases, 9 had symptoms leading to diagnosis, 5 had local pain or diffuse headache,1,3-5 1 had proptosis,7 1 had an enlarging frontal mass,9 and 2 had other neurologic symptoms.4 The remaining cases were identified as incidental findings when imaging was performed for nonassociated symptoms. Our case is the first reported in a child. In addition, although the majority of these lesions have been identified in the occipital bone with several cases identified in the frontotemporal region, this is the first to be reported in the sphenoid bone. We believe that the unique occurrence of this lesion within the lateral orbital wall of our patient led to proptosis and its diagnosis at an earlier age. Patient
photographs dating back 5 years confirm the slowgrowing nature of this benign lesion, with right brow fullness increasing during the 5 years preceding her presentation (e-Supplement 1). There is a wide differential diagnosis for palpable cranial abnormalities in children; however, the initial use of computed tomography imaging in this case aided in narrowing the possibilities after demonstrating that the lesion was centered in bone and that it was markedly expansile with extensive remodeling. In children, the differential for calvarial lesions includes epidermoid or dermoid cyst, eosinophilic granuloma, aneurysmal bone cyst, lymphatic or vascular malformations, cystic fibrous dysplasia, multiple myeloma, giant cell tumor, metastatic disease, rhabdomyosarcoma, Ewing sarcoma, osteogenic carcinoma, and osteogenic sarcoma. After magnetic resonance imaging with demonstration of CSF signal intensity of the lesion on all pulse sequences, the absence of enhancement, and the absence of a soft tissue component as well as the adjacent middle cranial fossa arachnoid cyst, we favored the diagnosis of intradiploic arachnoid cyst, especially when the patient’s clinical history was taken into account. In our case, the diffusionweighted images were degraded by artifact from the patient’s orthodontic braces; however, there was no gross increased signal intensity on these pulse sequences or peripheral enhancement, as might be expected if the lesion was an epidermoid cyst.8 An epidermoid cyst would also be observed in this setting; however, follow-up may vary because it may progress at a faster rate than an intradiploic arachnoid cyst. Surgical treatment of these lesions consists of craniectomy or craniotomy with fenestration of the cyst, excision of its pedicle, and repair of the dural defect, sometimes combined with implants to replace bony defects. Although
Journal of AAPOS
Volume 15 Number 6 / December 2011 surgical treatment was described in 13 of the 15 previously reported cases, it was predominantly to establish a histological diagnosis. If preoperative evaluation can establish this diagnosis in an otherwise-asymptomatic patient, observation with serial imaging is warranted.
Literature Search PubMed was searched without language or date restrictions for the following terms: intradiploic arachnoid cyst, intradiploic cyst, arachnoid cyst, orbital cyst, bone cyst, and sphenoid cyst. References 1. Thomas TA, Rout D. Nontraumatic intraosseous cerebrospinal fluid cyst with associated craniovertebral anomalies: A case report and suggested mechanism of formation. Neurol India 2010;58:122-4.
Journal of AAPOS
Sachdeva et al
603
2. D’Almeida AC, King RB. Intradiploic cerebrospinal fluid fistula: Report of two cases. J Neurosurg 1981;54:84-8. 3. Weinand ME, Rengachary SS, McGregor DH, Watanabe I. Intradiploic arachnoid cysts: Report of two cases. J Neurosurg 1989;70:954-8. 4. Hasegawa H, Bitoh S, Koshino K, Obashi J, Iwaisako K, Fukushima Y. Nontraumatic intradiploic arachnoid cysts—report of five cases. Neurol Med Chir 1992;32:887-90. 5. Alfieri A, Zona G, Cirillo S, Spaziante R. Intradiploic arachnoid cyst: Case report. Neuroradiology 1996;38:569-71. 6. Asahi T, Endo S, Akai T, Takaba M, Takaku A. Nontraumatic convexity intradiploic arachnoid cyst. Neurol Med Chir 1998;38:374-6. 7. Krupp W, Dohnert J, Kellerman NS, Seifer V. Intradiploic arachnoid cyst with extensive deformation of craniofacial osseous structures: Case report. Neurosurgery 1999;44:868-70. 8. Yamaguchi S, Hirohata T, Sumida M, Arita K, Kurisu K. Intradiploic arachnoid cyst identified by diffusion weighted magnetic resonance imaging: Case report. Neurol Med Chir 2002;42:137-9. 9. Iplikcioglu AC, Dinc C, Bikmaz K, Bek S, Gokduman CA, Cosar M. Nontraumatic intradiploic arachnoid cyst. Acta Neurochir 2006;148: 659-62.
