Orbital dermoid cyst

Correlation Between Radiologic and Histopathologic Features of Orbital Epidermoid and Dermoid Cysts

PURPOSE

Epidermoid cysts (EC) and dermoid cysts (DC) typically appear as well-circumscribed lesions on CT. This study aimed to clarify the radiologic and histopathologic characteristics of orbital EC and DC and to determine the correlations between them.

METHODS

The medical records of 69 patients who underwent surgery for orbital DC or EC at Samsung Medical Center between January 2001 and August 2016 were retrospectively reviewed. The size and location of the cysts, rim enhancement, homogeneity of contents, presence of hemorrhagic or calcific components, radiodensity of contents, and extent of bony remodeling were evaluated using CT. Additionally, the cyst lining and contents were examined histopathologically.

RESULTS

Among patients with orbital cysts, EC and DC were diagnosed in 10 (14.5%) and 59 (85.5%) patients, respectively. Further, 50.0% of EC and 79.7% of DC were located in the superotemporal quadrant of the orbit. On orbital CT, the average radiodensity of EC and DC was 18.9 ± 56.2 and -67.9 ± 63.3 HU, respectively. The cystic contents were more frequently homogeneous than heterogeneous in both EC and DC; however, the radiodensity of cysts differed significantly, which may be attributed to sebaceous gland activity. Focal bony notching, bone remodeling under pressure, and bony changes from dumbbell-shaped cysts were observed more frequently in DC than in EC.

CONCLUSIONS

Radiological and histopathological features are correlated in orbital EC and DC. Therefore, orbital EC and DC can be preoperatively differentiated using CT, based on the average radiodensity and bony remodeling.

Retrobulbar respiratory epithelial orbital cyst in a dog: A case report

A 10-month-old female, neutered French Bulldog presented with a history of unilateral right-sided intermittent conjunctivitis and exophthalmos. The patient suffered blunt force trauma to the right eye after a tennis ball impact approximately five months prior to presentation. Examination identified the patient was visual with exophthalmos, lateral strabismus, conjunctival hyperaemia, episcleral congestion, and papilloedema. Magnetic resonance imaging and ultrasonography identified an approximately two centimeter diameter fluid-filled structure directly posterior to the globe leading to displacement of the optic nerve and distortion of the posterior globe wall. Centesis of the lesion demonstrated neutrophilic and macrophagic inflammation with evidence of prior hemorrhage. Within four weeks, the structure had re-filled to its original size and was subsequently excised in its entirety, via a lateral orbitotomy. Histopathologic findings indicated a non-keratinising orbital cyst, the lining of which was consistent with a respiratory epithelial cyst. Recurrence had not occurred seven months' post-surgery. To the author's knowledge, previous reports of retrobulbar respiratory epithelial cysts have not been documented in animals.

Spheno-orbital Lesions-A Major Review of Nonmeningioma Causes

PURPOSE

To review the imaging features of the broad range of nonmeningioma lesions of the greater wing of the sphenoid (GWS) bone and adjacent orbit to assist clinicians in differentiating these lesions from each other and from the most common lesion of the GWS and adjacent orbit, meningioma.

METHODS

We reviewed 32 cases of spheno-orbital lesions involving the GWS from our own practice, as well as 109 published cases (total 141), with emphasis on available imaging features on computerized tomography (CT) and MRI. Features that might assist in differentiating meningioma from its mimics were analyzed for each lesion, including the presence of an osteoblastic or hyperostotic response, bone erosion or osteolysis, homogeneous hypo- or hyperintensity on T2-weighted MRI, leptomeningeal involvement, and the absence of a "dural tail" on contrast-enhanced MRI. The clinical and imaging features were also briefly summarized for each diagnostic group.

RESULTS

The largest diagnostic group was metastasis (67 cases, 47.5%). The most useful imaging features that helped differentiate meningioma from its mimics were the presence of bone erosion and the absence of a "dural tail." Other features were helpful in a small minority of cases only. Metastatic prostate cancer was the largest single group (21 cases), and 18 (85.7%) of these were osteoblastic and most closely mimicked meningioma. Prostate cancer patients were generally older than males with GWS meningioma. Almost all other (44/46, or 95.7%) metastatic lesions showed evidence of bone erosion. Almost half (30 of 61, 49.2%) of patients with metastasis presented without a known diagnosis of malignancy. Among children 16 years of age and less, Langerhans cell histiocytosis (10 cases), dermoid cyst (5), and Ewing's sarcoma (5) were the most common diagnoses.

CONCLUSIONS

A combination of a careful history and both CT and MRI gives information, which can best guide the management of patients with spheno-orbital lesions. Metastatic prostate cancer to the GWS most closely mimics GWS meningioma but can in most cases be differentiated on clinical and imaging features. Older males with hyperostotic lesions of the GWS should be investigated for prostate cancer. Other metastatic lesions and primary tumors of the GWS, as well as benign and structural lesions can readily be differentiated from meningioma on clinical and imaging features.

Giant Deep Orbital Dermoid Cyst Presenting in Infancy

ABSTRACT

Orbital dermoid cysts are benign choristomas that are very common in children and occur most often as a lateral or medial mass associated with the frontozygomatic or frontoethmoidal suture line. The authors present an unusual case of an occult giant deep orbital dermoid cyst in infancy that initially presented with a small, benign appearance and central upper eyelid location on clinical exam. Orbitotomy with complete excision prevented further ocular sequelae in this 11-month-old.

MR-Eye: High-Resolution Microscopy Coil MRI for the Assessment of the Orbit and Periorbital Structures, Part 2: Clinical Applications

In the first part of this 2-part series, we described how to implement microscopy coil MR imaging of the orbits. Beyond being a useful anatomic educational tool, microscopy coil MR imaging has valuable applications in clinical practice. By depicting deep tissue tumor extension, which cannot be evaluated clinically, ophthalmic surgeons can minimize the surgical field, preserve normal anatomy when possible, and maximize the accuracy of resection margins. Here we demonstrate common and uncommon pathologies that may be encountered in orbital microscopy coil MR imaging practice and discuss the imaging appearance, the underlying pathologic processes, and the clinical relevance of the microscopy coil MR imaging findings.

Intraconal orbital dermoid cyst: a rare location

Intraconal dermoid cysts are very unusual in routine clinical practice. Clinical symptoms depend upon the site and extension of the lesion. Though rare, proptosis, diplopia, and orbital pain are the presenting symptoms encountered in patients with an intraorbital dermoid cyst. Although radiology can be diagnostic, a complete correlation with the final histopathology is always mandatory for its confirmation. Endoscopic excision of the cyst ensures a complete cure for the disease without any intraoperative/postoperative complications.

Subconjunctival Lipid Leakage From Deep Orbital Dermoid Cysts

Orbital dermoid cysts are fairly common and arise by sequestration of surface ectoderm along skeletal suture lines during embryologic development. Although anterior dermoid cysts are generally evident in infancy, deeper cysts typically present with inflammatory symptoms in adulthood. The authors report the clinical and imaging features for 6 cases of deep orbital dermoid cysts that were identified by the presence of subconjunctival lipid droplets; to the authors' knowledge, this case report represents the largest series of dermoids with such a presentation. In the absence of prior vitreoretinal surgery, subconjunctival lipid droplets are an important clinical sign suggesting the presence of a deep orbital dermoid cyst.

Orbital and periorbital dermoid/epidermoid cyst: a series of 280 cases and a brief review

OBJECTIVE

To report one of the largest case series on periorbital and orbital dermoid/epidermoid cyst and to highlight some important and unusual findings.

METHODS

Retrospective analysis of 280 cases with orbital or periorbital dermoid/epidermoid cyst that presented over a period of 14 years.

RESULTS

Periorbital cyst was more than twice as common as orbital cyst. Majority of patients had bony changes with some unusual findings seen in cases with orbital cysts, that is, presence of fluid-fluid level, calcification in the wall, and coexistent double cysts in 19 (6.8%), 5 (1.8%), and 4 (1.5%) cases, respectively. Dumbbell dermoid cyst with connection in temporal fossa was seen in 16 (5.7%) cases. Subperiosteal location of orbital dermoid cyst was most destructive because of extensive bony invasion. Most of the periorbital cysts were removed in toto, whereas orbital cysts required decompression before removal. The histopathological diagnosis was dermoid cyst in 250 (89%) cases and epidermoid cyst in 30 (11%) cases. In 69 (25%) cases, there was a chronic inflammatory response.

CONCLUSIONS

We recommend imaging in all patients with orbital dermoid to rule out dumbbell or subperiosteal extension. Also, we advocate early removal of all dermoid cysts in view of bone changes seen in majority of our cases and presence of inflammatory cells in 25% of cases.

Older age and larger cyst size in children with spontaneous rupture of periorbital dermoid cysts

We analyzed clinical and histopathologic data of 97 pediatric patients who underwent excision of dermoid cysts. On review, 16.5% of the sample population demonstrated localized chronic inflammatory changes, including the presence of giant cells and epithelial disruption. These features were considered indicative of prior cyst rupture. Age at time of initial presentation was significantly older and cyst size was significantly larger in patients with histopathologic signs of previous rupture. Longer time to presentation and time to excision were associated with increased odds of spontaneous rupture.

The spectrum of orbital dermoid cysts and their surgical management

PURPOSE

The purpose of this study is to describe a spectrum of surgical approaches to orbital dermoid cysts, influenced by the anatomic location of the expanded cyst wall and other factors.

METHODS

In this retrospective case series, we reviewed cases of dermoid cysts surgically excised during a 39-year period (1977-2016). Cysts were categorized according to the location of the expanded cyst wall and other considerations. The impact of these factors on surgical management was determined.

RESULTS

We identified six dermoid cyst growth patterns based on the anatomic location of the expanded cyst wall that influence the surgical approach: anterior to the frontozygomatic suture (FZS), superior to the FZS, medial to the FZS and other lateral wall sutures, traversing the FZS and other lateral wall sutures, nasoglabellar, and sinus tract from the orbit to the skin. Two additional factors influencing surgical methodology included satellite inflammatory pseudocysts and recurrence after surgical resection.

CONCLUSION

Orbital dermoid cysts are not monolithic lesions. Functional and aesthetic outcomes can benefit from considering the anatomic pattern of cyst wall expansion and other factors in their surgical management.

Minimally invasive treatment of pediatric head and neck dermoids: percutaneous drainage and radiofrequency coblation

BACKGROUND

Dermoids are common benign head and neck cysts in children containing a variety of different skin elements. Current standard treatment is surgical removal that sometimes requires extensive dissection to ensure complete resection and often leaves unwanted facial scarring. A minimally invasive treatment alternative should offer a similar rate of success with a decrease in operative complexity, recovery time and postoperative scarring.

OBJECTIVE

To assess the outcomes of our minimally invasive percutaneous treatment of head and neck dermoids, we reviewed our 9-year interventional radiology (IR) department experience.

MATERIALS AND METHODS

The medical records, imaging and procedural details were reviewed from a cohort of pediatric patients with dermoids treated in our IR department from January 2009 through February 2018. Patients in the study underwent ultrasound (US)-guided cyst puncture, 3% Sotradecol (sodium tetradecyl sulfate [STS]) emulsification of the thick cyst contents allowing complete drainage, and radiofrequency coblation of the cyst wall.

RESULTS

In this retrospective study, we report on 22 dermoids in 21 patients. The average patient age was 3 years. Twenty-one of the 22 dermoids were successfully treated for an overall success rate of 95%. Four intraosseous dermoids were successfully treated using computed tomography (CT) guidance instead of, or in addition to, US. Average follow-up time was 22 months.

CONCLUSION

The combination of percutaneous cyst drainage using STS as an emulsifying agent followed by radiofrequency coblation is a safe, effective, minimally invasive treatment for pediatric patients with head and neck dermoids.

Multilobular dermoid cyst of the orbit

Dermoid cysts are histologically defined as surface epithelium encapsulating an inner lumen. They are well described in the literature as discrete, single masses, either circumscribed or dumbbell-shaped, with or without a longstanding fistula. Chronic granulomatous inflammation is often a feature of dermoid cysts, contributing to local soft tissue and bony destruction. Isolated multicystic dermoids are not well described. We present a case of a multilobular dermoid characterized both radiographically and histopathologically. These findings may be attributed to repeated rupture and reformation of the dermoid cyst. When possible, our experience favours early excision of orbital dermoid cysts to minimize morbidity.

Orbital Dermoid Cyst: Classification and its Impact on Surgical Management

PURPOSE

Analysis of different clinical types of orbital dermoid cyst, and studying the impact of preoperative classification on the proposed surgical procedure.

METHODS

A retrospective study of orbital dermoid cyst cases. The clinical and imaging data were reviewed. The different types of dermoid were recorded as superficial or deep, lateral or medial, exophytic or endophytic. The deep dermoids were classified according to their site and continuity of the cyst wall. The operative approach, intraoperative, and/or postoperative complications were recorded.

RESULTS

The study included 153 cases of orbital dermoid. The superficial lesions represented 68.6%, of which 74.3% were lateral and 61.0% were endophytic. Intraoperative cyst perforation was recorded in 56.3% of exophytic cases approached through crease incision, and recurrence occurred in 6.3%. Defective cyst wall was found in 31.25% of deep orbital dermoid. Surgery was complicated by cyst rupture when excision was attempted, and recurrence was recorded in one case. Exposure, intended evacuation, and dissection of the cyst wall were better surgical approaches for these cases without reported complications.

CONCLUSION

Preoperative classification of orbital dermoid had an important effect on the surgical procedure. Endophytic superficial lesions were approached through crease incision without complications, while exophytic lesions were better approached through infrabrow incision. Deep orbital lesions with defective wall were better approached through exposure, intended evacuation, dissection, and excision of the remaining cyst wall.

Quantitative characterization of growth rate of an incidental deep dermoid cyst in a child using sequential magnetic resonance imaging

When orbital lesions are discovered incidentally, some have advocated observation given the slow-growing nature of deep dermoids; however, little has been published regarding the true growth potential of these tumors. We describe a case of an incidental deep orbital dermoid cyst in a 7.5-month-old girl with retinoblastoma. The cyst was monitored with five sequential magnetic resonance imaging studies of the orbit over 23 months with careful documentation of growth. The cyst was surgically removed without complication, and histopathology confirmed the diagnosis of dermoid cyst. This case represents the first published quantitative measurement of dermoid growth potential and highlights the need for close early monitoring in incidentally discovered cases.

Upper blepharoplasty approach to frontozygomatic dermoid cysts

OBJECTIVES

Dermoid cysts are common periorbital lesions in children. Traditional surgical approaches have included incisions over the mass; above, below, or through the brow; and parallel to the superior orbital rim and the Lynch incision, as well as lateral canthotomy. We aimed to present experience of Alder Hey Children's Hospital on frontozygomatic dermoid removal through a blepharoplasty incision. In this article, we also aimed to review the current literature, describe the operative technique clearly, and offer reasonable explanations for the operative choices made based on our experience of the clinical anatomy and pathology.

METHODS

Thirty-four children were operated on (19 girls and 15 boys), aged 1 to 11 years, between 2005 and 2008. The lesions were left sided in 14 patients and right sided in 20 patients. Preoperative computed tomographic/magnetic resonance imaging scan was generally not used, except in cases where the cyst was more than 1 cm away from the brow margin.

RESULTS

All cysts were completely excised. At surgery, all cysts were adherent to the periosteum, and 3 were subperiosteal. None extended through the bone into the orbit. The average operating time was 30 minutes. The average follow-up duration was 1 year. The only complications were early mechanical ptosis in 3 children, which completely resolved; the majority had an uneventful postoperative course. There were no recurrences, and in all patients, scar camouflage was described as excellent.

CONCLUSIONS

This interesting and extremely effective technique provides excellent scar camouflage with no lid or ocular dysfunction.

Orbital Dermoids in Children

Orbital dermoid cysts are benign congenital choristomas. They are common in pediatric population, developing adjacent to suture lines, most commonly located in antero-lateral fronto-zygomatic suture, and are slowly progressive. Complete surgical excision without rupture of cyst is the standard of care. Deep orbital cysts cause proptosis, require imaging, and may present a surgical challenge with a difficult approach. Rupture of the cyst leads to severe inflammatory reaction in surrounding tissues. Overall prognosis remains good with isolated reports of malignancy masquerading as dermoid cysts.

Percutaneous drainage and ablation of orbital dermoid cysts

BACKGROUND

Vision-threatening intraorbital dermoid cysts have traditionally been treated by complete surgical resection. Such radical surgical intervention may pose serious risks to both vision acuity and cosmesis. We describe a novel, minimally invasive approach for the treatment of orbital dermoid cysts.

METHODS

This is an interventional retrospective case series. Two patients (17 and 4 years) presented with large intraorbital dermoid cysts. The first patient had a dumbbell-shaped lesion involving the temporalis fossa and superotemporal orbit. The second patient had a large, superior intraorbital lesion. Both patients presented with visual disturbance, globe displacement, and eyelid ptosis. A series of techniques were developed and implemented for percutaneous access, drainage, and catheter-based ablation (dual drug technique) of both orbital dermoid cysts. Initial access was gained with a 14-gauge angiocatheter needle system, followed by serial emulsification and drainage of the cyst contents. A 5-French catheter was coaxially placed for fluoroscopic contrast cyst definition and subsequent dual drug chemical ablation (sodium tetradecyl sulfate and ethanol). Suction drainage was maintained for 24 hours following ablation.

RESULTS

Radiological and clinical evaluation demonstrated complete resolution of the dermoid cysts with no recurrence at 12-month follow-up in the first patient and 3 months in the second patient. Cosmetic results were excellent. Patients reported no pain and there were no neurologic, oculomotor, infectious, hemorrhagic, or other complications.

CONCLUSIONS

Minimally invasive percutaneous drainage and ablation appears to be a promising treatment for large orbital dermoid cysts which would otherwise require extensive surgery to excise. Collaboration of an ophthalmologist and interventional radiologist is essential for evaluation, treatment, and follow-up.

Dermoid Cyst of Conjunctival Origin

A 22-year-old man with a recurrent intraconal cystic mass of the orbit presented with proptosis, motility restriction, and optic disc edema. On initial surgery, the cyst wall showed nonkeratinized cuboidal epithelium with adnexal structures. After recurrence, repeat histopathologic evaluation again showed nonkeratinizing conjunctival epithelium with goblet cells. The diagnosis was consistent with a dermoid cyst of conjunctival origin. Our review of the literature found 29 previous cases in the literature. Unlike typical cutaneous dermoids, conjunctival dermoids occur in young adults and are usually located in the nasal or superonasal deep orbit. The location and adnexal structures associated with these lesions suggests derivation from embryonic epithelium destined to become caruncle.

Orbital cysts of childhood—classification, clinical features, and management

There is little in the literature about the clinical spectrum of orbital cysts of childhood and no comprehensive classification has been proposed. The authors propose a classification of orbital cysts of childhood and review their clinical features, pathology, and management. The major categories in the classification include cysts of surface epithelium, teratomatous cysts, neural cysts, secondary cysts, inflammatory cysts, and noncystic lesions with cystic component. Cysts of the surface epithelium are further divided into simple epithelial cyst (epidermal, conjunctival, respiratory, and apocrine gland), and dermoid cyst (epidermal and conjunctival). Epidermal dermoid cyst (dermoid) is by far the most common orbital cystic lesion in children, accounting for over 40% of all orbital lesions of childhood and for 89% of all orbital cystic lesions of childhood that come to biopsy or surgical removal. Neural cysts include those associated with ocular maldevelopment (congenital cystic eye and colobomatous cyst) and those associated with brain and meningeal tissue (cephalocele and optic nerve meningocele). The most important secondary cyst is mucocele that can occur in children with cystic fibrosis. Inflammatory cysts are generally due to parasitic infestations and are more common in tropical areas of the world. Noncystic lesions that can have a cystic component include adenoid cystic carcinoma, rhabdomyosarcoma, lymphangioma, and others. Each type of cyst has rather characteristic, but not pathognomonic, clinical features. Computed tomography and magnetic resonance imaging can help differentiate a cystic lesion from a solid tumor, suggest the type of cyst, and help in planning management. The pathology varies with the cells that line the cyst and with the inflammatory agent. Management varies from local excision to observation, depending on the location and type of cyst. Orbital cysts of childhood can be classified into categories, based mainly on their histopathology. The clinical, radiologic, and histopathologic features can be correlated with the classification in order to better evaluate a child with a cystic lesion in the orbit.

Bilateral Frontozygomatic Dermoid Cysts

A unique case of frontozygomatic dermoids in a 4-year-old child is presented. A bilateral, synchronous presentation in this location has not been reported previously in the literature. Both lesions were excised concurrently through upper eyelid crease incisions. The etiology, natural history, management, and prognosis of dermoids are reviewed.

Clinical, radiological and pathological examination of periocular dermoid cysts: evidence of inflammation from an early age

INTRODUCTION

Periocular dermoid cysts are common and leakage of the lipid or keratin contents leads to an inflammation-often asymptomatic-around the cyst, which may cause adherence of the dermoid cyst to neighbouring structures.

PURPOSE

To investigate the frequency of clinical and radiological signs of inflammation with periocular dermoid cysts, to relate this to the histopathological examination of the excised specimens, and to assess whether the degree of inflammation is related to age at presentation.

PATIENTS AND METHODS

A retrospective non-comparative series of 124 patients with periocular dermoid cysts that had undergone imaging. Case-notes were reviewed for clinical and histopathological details and there was independent review of the radiological imaging.

RESULTS

Surgery was undertaken at between 1 and 66 years of age, most patients being under 10 years, and the duration of symptoms varied from 4 weeks to 30 years. Symptoms of inflammation-mainly intermittent lid swelling with localised redness and pain-occurred in all age groups, the proportion being greatest in the fourth decade. Clinical signs of inflammation at the time of clinic visit were relatively few, although 8% had some localised erythema and 7% had tenderness at the site of lesion. In more than two-thirds of the excised cysts, pathological examination demonstrated various degrees of chronic inflammation, even in those cysts removed before the age of 5 years.

CONCLUSION

Even if the patient does not have symptoms or signs of inflammation, most periocular dermoid cysts show histological evidence of inflammation due to leakage of the lipid and keratin contents from the cyst, the incidence being similar at all ages.

Computed tomography of orbital dermoids: a 20-year review

AIM

To review the computed tomographic images of orbital dermoid cysts referred to our institution over a 20-year period.

MATERIALS AND METHODS

The CT images of 160 patients with histologically proven orbital dermoid cysts were reviewed and patient demographics and cyst characteristics were recorded.

RESULTS

A total of 160 dermoid cysts were seen, 87 were in male and 73 in female patients with mean ages of 29 and 27 years respectively. The lateral aspect of the orbit was the most common site (69%, 111/160). Eighty-five percent (136/160) had adjacent bone changes, 46% (73/160) were of lower CT attenuation than the water in the vitreous body, 14% (22/160) had calcification, 5% (8/160) had fluid levels, 73% (117/160) had a visible wall and 80% (129/160) had no soft tissue present outside the cyst.

CONCLUSION

Our study shows that orbital dermoids are frequently located at the lateral canthus. Bone sparing, calcification, fluid level, no visible wall and no abnormal soft tissue outside the cyst are infrequent. A CT attenuation similar to fat is relatively frequent. Although many lesions are typical, the range of appearances is wide.

Primary temporal fossa dermoid cysts. Characterization and surgical management

OBJECTIVE

To detail the characteristics and management of rarely reported and incompletely described dermoid cysts originating in the temporal fossa.

DESIGN

Retrospective case series.

PARTICIPANTS

Five patients ranging from 2 to 38 years of age with a mass in the temporal region (posterior to the lateral orbital rim) participated.

INTERVENTION

Computed tomography (CT) and excisional biopsy were performed.

MAIN OUTCOME MEASURES

Clinical and CT characteristics and surgical outcomes were measured.

RESULTS

Computed tomography showed cystic lesions, originating from the region anterior to the confluence of the greater wing of the sphenoid, frontal, and zygomatic bones. Displacement of the anteriormost portion of the temporalis muscle was common. Three cysts were isolated to the temporalis fossa, while two showed more extensive bony erosion and extension into the cranial and orbit cavities. At surgical excision, gross rupture of the cysts was noted in two cases, and two were completely liquefied. Histopathology showed variable inflammation surrounding all of the dermoid cysts. All patients did well after surgery.

CONCLUSIONS

Dermoid cysts may infrequently occur "primarily" in the temporal fossa. Bone involvement and anterior temporalis muscle displacement are common. An origin from the area anterior to the confluence of the greater wing of the sphenoid, frontal, and zygomatic bones is seen. A coronal approach facilitates wide exposure and excision. When dural extension is suggested on CT, neurosurgical assistance may be required.

Deep frontotemporal dermoid cyst presenting as a discharging sinus: a case report and review of literature

The commonest location for dermoid cysts in the head and neck is at the frontotemporal or brow region. They usually present as discrete slow growing masses located superficially at the angle of the brow. The presentation as a discharging sinus in the frontotemporal region is rare. In contrast, it is common for nasal dermoids to present as sinuses or fistulae (10-45%) and with a tract extending deep to involve the underlying bone or intracranium. In view of their differences in presentation, preoperative CT scans are generally recommended for the nasal dermoids but not for the frontotemporal dermoids. We report a rare case of a deep frontotemporal dermoid cyst presenting as a discharging sinus at the right temporal region in a girl aged 2 years and 6 months. It had a sinus tract extending deep to form an intraosseous cyst in the frontal and sphenoid bone. The base of the cyst was attached to the dura of the middle cranial fossa. Only a few similar cases were reported in the literature. In the light of our experience with this case, we recommend that this rare type of frontotemporal cyst sinus be operated only after a CT or MRI scan.

Atypical choristomatous cysts of the orbit

BACKGROUND

The commonset choristomatous cysts of the orbit are dermoid and epidermoid cysts, which are lined by kerantinizing squamous epithelium. They typically occur in the superior orbit, most commonly superotemporally. Other types, lined by different epithelia, and other orbital sites are much less common.

METHODS

Five cases of atypical orbita cystic choristomas that presented over the past 6 years are reported. The clinical and radiological features, surgical approach and findings, and histology, are described. Similar cases from the literature are reviewed and possible aetiology discussed.

RESULTS

Four of the cysts were lined by a non-keratinizing epithelium resembling conjunctiva; two had adnexal structures in their walls. Compared with typical dermoid and epidermoid cysts, these 'conjunctival dermoids' and 'conjunctival cysts' of the orbit tended to present later in life, none were associated with bony defects, and three of the four occurred in the superomedial quadrant. One case occurred inferiorly, a rare site for orbital conjunctival dermoids and cysts, or typical dermoids and epidermoids. The fifth case, also inferior, is an example of a cyst within choristomatous lacrimal tissue.

CONCLUSION

Choristomatous cysts of the orbit may occur with non-keratinizing epithelial linings, and such cysts tend to differ clinically from the commoner dermoids and epidermoids. They may also occur in atypical sites such as the inferior orbit.

Aetiology and management of proptosis in young Jordanians

Sixty-two cases of proptosis in children and adolescents were prospectively evaluated in a specialized practice at Irbid, North Jordan, during the period between 1990 and 1994. Inflammatory orbital conditions were seen in 27 patients (43.5%). The causes of orbital cellulitis were identified in 15 out of 25 cases. Predisposing factors and outcome were analyzed. Vasculogenic lesions were encountered in 15 cases, five of which were subperiosteal orbital haematomas. Twelve cases with structural lesions ranging from a benign cystic dermoid to craniostenosis were managed in various ways. A rare case of primary hydatid disease in the orbit was also seen. Results of surgical treatment and outcome in each condition were assessed. Eight cases (14%) were neoplastic in nature. A rare case of retinoblastoma which presented as orbital cellulitis is included. Orbitotomies were performed for excision biopsy, mass removal and decompression or exenterations of the orbit, with no serious complications. No cases of proptosis owing to thyroid ophthalmopathy or systemic diseases were seen. The relatively low frequency of secondary orbital retinoblastoma among Jordanian children is compared with that in related reports from other countries.

Orbital dermoid cysts located within the lateral rectus muscle

BACKGROUND

Two patients, a 13-year-old girl and a 31-year-old man, had an orbital dermoid tumor located in the lateral rectus muscle. This unusual location of dermoid tumors has not been reported previously.

METHODS

Computed tomography and magnetic resonance imaging showed a cystic mass within the belly of the lateral rectus in each patient. Surgical excision through a lateral orbitotomy showed a well-circumscribed mass surrounded by lateral rectus fibers. No periorbital attachment was noted.

RESULTS

Results of histopathologic evaluations showed a dermoid cyst. Postoperatively, the diplopia and proptosis resolved. In one patient, an unusual subconjunctival deposition of fat droplets was seen.

CONCLUSION

The findings in patients demonstrate an unusual presentation of dermoid cysts and make an addition to the differential diagnosis of enlarged extraocular muscles.

The frequency and clinical significance of bone involvement in outer canthus dermoid cysts

Periorbital dermoid cysts should be removed because they commonly leak their irritant contents into the surrounding tissues. The underlying bone may, however, be involved in patients with dermoid cysts at the outer canthus. Computed tomography studies of 70 patients (43 men and 27 women, aged 30 months to 63 years, mean 29 years) with proved dermoid cysts of this type were reviewed. The lesion was always unilateral; 34 were on the left. The bone of the lateral wall and superotemporal angle of the orbit showed the following abnormalities, often in combination: pressure erosion in 61 cases and an otherwise abnormal shape, probably developmental, in 55; the dermoid cyst entered a tunnel or canal through the lateral wall in 24; a blind pit or crater in 15; and a cleft in 20; many patients also showed abnormal bone texture. These findings are extremely important for planning adequate surgery, and indicate that bony involvement is much more frequent than previously appreciated.

Intradiploic epidermoid cysts of the bony orbit

Epidermoid cysts originating within the diploic space of the bony orbit are rare. The authors retrospectively studied four patients with an intradiploic epidermoid cyst of the orbital bones to investigate the clinical and the computed tomographic (CT) findings. The clinical presentation was dependent on the location of the slowly expanding epidermoid cyst. The sphenoid bone was involved in three patients and the frontal bone in one patient. Proptosis caused by intraorbital extension of the mass was the most common presenting sign. The findings on high-resolution CT scans appeared to be specific for intradiploic epidermoid cysts. The typical sclerotic margin, which is diagnostic of intradiploic epidermoid cysts, can be demonstrated by CT scans with a bone window setting.