Hydatid Disease of The Orbit - Lesson Forgotten! - aioseducation
Hydatid Disease of The Orbit - Lesson Forgotten! - aioseducation
Hydatid Disease of The Orbit - Lesson Forgotten! - aioseducation
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Best <strong>of</strong> Best Free Papersthe histopathological diagnosis was available. Postoperatively, the patient whounderwent an enucleation was fitted with a suitable prosthetic implant.Histopathological diagnosis: <strong>The</strong> samples included excision <strong>of</strong> cyst in allcases, with fluid aspiration in one and enucleation <strong>of</strong> the phthisical eye in onepatient. All cases showed the classic laminated membrane. Germinal layer wasidentified in 4 cases. One case showed fibrous capsule with skeletal musclefibres and an inner layer <strong>of</strong> necrotic material with granulation tissue. Sectionsthrough the eye showed a scarred cornea with areas <strong>of</strong> fibrous and osseousmetaplasia. A diagnosis <strong>of</strong> phthisical eye with osseous metaplasia was made.DISCUSSION<strong>Hydatid</strong> disease is a parasitic disease caused by the adult tapewormEchinococcus granulosa. A Pubmed English literature search <strong>of</strong> “<strong>Hydatid</strong>disease and <strong>Orbit</strong>” revealed 110 publications. <strong>The</strong> largest series were publishedfrom Argentina (35 cases, 1944 and 1985); South Africa (11, 1977), China (18cases 1999). We report a series <strong>of</strong> 7 patients <strong>of</strong> orbital hydatid disease seen overmore than a decade at a tertiary eye care centre in Southern India.<strong>The</strong> modern name <strong>of</strong> hydatid cyst was coined by Rudolphi in 1800 and wasderived from the Greek word hydatid meaning a drop <strong>of</strong> water. Humaninfestation is caused by the larval stage <strong>of</strong> the tapeworm Echinococcusgranulosa. Man is the accidental intermediate host in the life cycle. Dogs,wolves, cats or foxes are the definitive hosts for the adult worm while cattleare the intermediate hosts. 2,3,4,5,6 Humans become infected by contact with thedefinitive host or by consuming water or vegetables contaminated with thefaeces <strong>of</strong> these animals. Ova hatch as embryos in the human intestinal tract,pass into the portal venous system and seed the liver and lungs. When theflesh or visceral organs <strong>of</strong> intermediate hosts are eaten by canines, the cysttransforms to adult worms in their intestine and a new cycle starts. 7<strong>Orbit</strong>al involvement is exceptionally rare (1%), documented by a recent studyfrom a highly endemic region, which found only 18 cases <strong>of</strong> orbital cysts out<strong>of</strong> 3,736 patients with echinococcosis, representing 0.3% <strong>of</strong> the total cases <strong>of</strong>hydatid disease. 6 Much has changed in the management and our dependenceon serological tests with imaging technology taking the lead in diagnosisat present. <strong>The</strong> cysts grow on at average <strong>of</strong> 1.5 cm/year. Due to the limitedspace in the orbital cavity, it would be logical to expect that the patients wouldbecome symptomatic and present early. 7,11 However, on the contrary, themean duration <strong>of</strong> symptoms in this study was 28.5 months. <strong>The</strong> mean age <strong>of</strong>presentation is 25.7 yrs. This is marginally older than what other larger caseseries have reported. Both indicate a possible delay in presentation or delay indiagnosis. 7Clinical diagnosis at the time <strong>of</strong> referral was made in only 2 <strong>of</strong> 8 cases. This
70th AIOC Proceedings, Cochin 2012may indicate a low index <strong>of</strong> suspicion among ophthalmologists about thevarious manifestations <strong>of</strong> hydatid disease, even in endemic regions such asours. Thus, a high index <strong>of</strong> suspicion is warranted for, especially in youngerpatients presenting from endemic areas, where farming and sheep rearingform the predominant source <strong>of</strong> livelihood. Gradual onset proptosis andprogression <strong>of</strong> the proptosis in a quiet eye should suggest this condition eventhough hydatid disease is an uncommon cause <strong>of</strong> proptosis. 6,8 A high index<strong>of</strong> suspicion, endemicity and cyst characteristics on imaging contents shouldhelp in differentiating hydatid from other causes <strong>of</strong> proptosis.<strong>The</strong> triad <strong>of</strong> symptoms described in hydatid cyst <strong>of</strong> the orbit are proptosis,tumour and pain. Proptosis is the most common sign. We report 3 cases thathad RAPD suggesting chronicity leading to optic nerve involvement at thetime <strong>of</strong> presentation, which was due to a delay in acquiring treatment. 6,7Non-specific clinical signs make diagnosis using appropriate imaging a must.USG detects single or multi lobulated cysts with echoluscent centres. CT scandemonstrates cystic structures with calcification. In a paper published by S.M.Betharia et al, USG was found to be more helpful in the preoperative diagnosis<strong>of</strong> <strong>Hydatid</strong> disease than CT. <strong>The</strong>y have also described a diagnostic double wallsign on USG. 9<strong>The</strong> differential diagnoses <strong>of</strong> well-defined, thin-walled, unilocular lesion onCT scan include dermoid, teratoma, and chronic hematic cyst. <strong>The</strong> imagingfeatures <strong>of</strong> hydatid cysts depend on the unique trilaminated cyst wall, each afew millimetres thick. Free scolices and brood capsules produce hydatid sand.<strong>The</strong> differential <strong>of</strong> a parasitic cyst was provided in 4 out <strong>of</strong> which hydatidcyst was provided as a differential in 2. Additional supportive evidence isfrom Casoni and Weinberg skin tests, indirect haemagglutination test, andELISA; though studies have shown these tests have a low sensitivity and thusdo not prove helpful in providing a preoperative diagnosis. Surgery with a2, 3,4,5,6histopathological association has provided the most definitive diagnosis.Histopathology <strong>of</strong> the cyst consists <strong>of</strong> a laminated ectocyst and an inner cellularendocyst (germinal layer). <strong>The</strong> ectocyst contained mucopolysaccharide whichwere strongly positive with the PAS stain. <strong>The</strong> germinal layer gives rise todaughter cysts, which have an ectocyst and a germinal endocyst. <strong>The</strong> daughtercyst may produce pin-head sized vesicles called brood capsules. <strong>The</strong>y containa large number <strong>of</strong> scolices, which later develop into the future heads <strong>of</strong> theadult tape worm. 8Surgical management resulted in clinical resolution <strong>of</strong> orbital hydatid diseasein 100% <strong>of</strong> patients. We believe early diagnosis and treatment <strong>of</strong> orbital hydatiddisease may limit eventual fibrosis <strong>of</strong> the extra ocular muscles and minimizeresidual deficit. USG and CT both in our experience are reliable parameters for