Hydatid Disease of The Orbit - Lesson Forgotten! - aioseducation

Best of Best Free Papersthe histopathological diagnosis was available. Postoperatively, the patient whounderwent an enucleation was fitted with a suitable prosthetic implant.Histopathological diagnosis: The samples included excision of cyst in allcases, with fluid aspiration in one and enucleation of 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 of necrotic material with granulation tissue. Sectionsthrough the eye showed a scarred cornea with areas of fibrous and osseousmetaplasia. A diagnosis of phthisical eye with osseous metaplasia was made.DISCUSSIONHydatid disease is a parasitic disease caused by the adult tapewormEchinococcus granulosa. A Pubmed English literature search of “Hydatiddisease and Orbit” revealed 110 publications. The largest series were publishedfrom Argentina (35 cases, 1944 and 1985); South Africa (11, 1977), China (18cases 1999). We report a series of 7 patients of orbital hydatid disease seen overmore than a decade at a tertiary eye care centre in Southern India.The modern name of hydatid cyst was coined by Rudolphi in 1800 and wasderived from the Greek word hydatid meaning a drop of water. Humaninfestation is caused by the larval stage of 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 of 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 of intermediate hosts are eaten by canines, the cysttransforms to adult worms in their intestine and a new cycle starts. 7Orbital involvement is exceptionally rare (1%), documented by a recent studyfrom a highly endemic region, which found only 18 cases of orbital cysts outof 3,736 patients with echinococcosis, representing 0.3% of the total cases ofhydatid disease. 6 Much has changed in the management and our dependenceon serological tests with imaging technology taking the lead in diagnosisat present. The cysts grow on at average of 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 of symptoms in this study was 28.5 months. The mean age ofpresentation 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 of referral was made in only 2 of 8 cases. This

70th AIOC Proceedings, Cochin 2012may indicate a low index of suspicion among ophthalmologists about thevarious manifestations of hydatid disease, even in endemic regions such asours. Thus, a high index of suspicion is warranted for, especially in youngerpatients presenting from endemic areas, where farming and sheep rearingform the predominant source of livelihood. Gradual onset proptosis andprogression of the proptosis in a quiet eye should suggest this condition eventhough hydatid disease is an uncommon cause of proptosis. 6,8 A high indexof suspicion, endemicity and cyst characteristics on imaging contents shouldhelp in differentiating hydatid from other causes of proptosis.The triad of symptoms described in hydatid cyst of 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 of 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 diagnosisof Hydatid disease than CT. They have also described a diagnostic double wallsign on USG. 9The differential diagnoses of well-defined, thin-walled, unilocular lesion onCT scan include dermoid, teratoma, and chronic hematic cyst. The imagingfeatures of hydatid cysts depend on the unique trilaminated cyst wall, each afew millimetres thick. Free scolices and brood capsules produce hydatid sand.The differential of a parasitic cyst was provided in 4 out of 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 of the cyst consists of a laminated ectocyst and an inner cellularendocyst (germinal layer). The ectocyst contained mucopolysaccharide whichwere strongly positive with the PAS stain. The germinal layer gives rise todaughter cysts, which have an ectocyst and a germinal endocyst. The daughtercyst may produce pin-head sized vesicles called brood capsules. They containa large number of scolices, which later develop into the future heads of theadult tape worm. 8Surgical management resulted in clinical resolution of orbital hydatid diseasein 100% of patients. We believe early diagnosis and treatment of orbital hydatiddisease may limit eventual fibrosis of the extra ocular muscles and minimizeresidual deficit. USG and CT both in our experience are reliable parameters for