Multivesicular Mediastinal Hydatid Cyst

A unique case of multivesicular mediastinal hydatid cyst without associated pleuropulmonary hydatidosis is presented. The relevant literature has been reviewed.

Introduction

Hydatid disease is prevalent in Yavatmal district of Maharashtra which is a tribal zone (Banjara Community). Literature mentions that about 2/3rd of all hydatid cysts in man occur in liver.¹ Hydatid cyst outside the liver but within peritoneal cavity are uncommon although described in spleen, pancreas, ovaries as well as disseminated in abdominal and pelvic cavities.¹ Third commonest site is hydatid cyst of lung occurring in 15% of cases.² But hydatid cyst of mediastinum without pleuropulmanary hydatid disease is not seen. Hydatid cyst of liver and other abdominal hydatids are frequently multivesicular but 90% of pulmonary hydatids are single contain no daughter cyst. Hydatid cyst in mediastinum is extremely rare and that too multivesicular is not reported in literature.

Hydatid disease has been given various names viz : Liver full of water, watery tumour of the chest, etc.⁴ The term hydatid cyst was however coined up by Rudolpti in 1800 and has been derived from Greek word ‘Hydatid’ meaning a drop of water.⁴ Though liver is traditionally considered as first filter and lungs the second filter, it is observed that lungs may be affected without involving the liver.^5,6 Though it is observed that normal method of transmission of hydatid disease is by ingestion of eggs, cysts can develop of eggs are inhaled directly into lungs.⁷ It is again postulated that some other alternative routes of infection either via intestinal lymphatics, thoracic duct or superior vena cava bypassing the liver may be responsible for giving rise to pulmonary hydatid disease.⁸ Perhaps such an abnormal route may be the explanation for development of hydatid cyst in such unconnected tissue as breast, thyroid, bone, submandibular salivary gland and mediastinum as in the present case.

Case Report


	Fig. 1 : Chest radiograph showing mediastinal mass.

	Fig. 2 : Intraoperative photo showing mediastinal hydatid with daughter cysts

A 50 year old lady was admitted for hydatid cyst of liver. On routine chest radiography lung fields were clear and upper mediastinal mass was noted. (Fig. 1). Ultrasonography was done which showed a cystic mass. Patient explored by right lateral thoracotomy incision. Lung was normal. There was cystic mass in anterior mediastinum. Clear fluid aspirated. Mediastinal pleura incised. Pericyst incised. (Fig. 2). Laminated membrane with multiple daughter cyst were removed. Post operative course was uneventful. Patient was discharged on 10th postoperative day.

Discussion

Pulmonary hydatid disease occurs in 15% of cases.² The cysts are usually single and univesicular i.e. do not contain daughter.³ Literature mentions that formation of daughter cyst depends not only as immunologic relationship between parasite and human but also on resistance offered by the enveloping structures.¹ If resistance offered is more primary cyst ruptures and pieces of germinal epithelium form daughter cysts.¹ As lung tissue offers least tresistance the lung cysts are usually univesicular as compared to liver cyst which usually contain daughter cyst, because of its tissue resistance.

The incidence of cystic lesions of the mediastinum is 20%. They include 1) Pericardial cyst, 2) Bronchogenic cyst, 3) Enterogenous cyst, 4) Dermoid cyst.⁹ Literature mentions that secondary pleural hydatid disease is an occasional but serious complication of rupture of Lung cystinto pleura or of ill executed surgery.² Multiple cyst grow widely throughout the pleura and may invade the chest wall diaphragm and mediastinum.² In such cases Radical pleuropneumonectomy offers the only hope of eradicating the disease² as albendazole group of drugs are yet to be established for cure of disseminated hydatidosis. But isolated hydatid cyst of mediastinum and that to containing daughter cyst is not yet reported in the literature.

Hence, a unique case of isolated mediastinal hydatid cyst containing daughter cysts, without associated pleuro pulmonary hydatid disease is hereby presented.

References

1. Maingot’s abdominal operations. 8th edition, page no. 1606-24.

2. Bailey and Loves short practice of surgery. 21st edition, page no. 855-56.

3. JP Singh and Pradeep Garg. Multiorgan pediatric hydatid disease. Ind J Surg 1993; 55; 222-24.

4. Romero-Torres R, Campbell JR. An inerpretive review of surgical treatment of hydatid disease Surg Gynac Obst 1965; 121 : 851.

5. Gupta JC, et al. Hydatid disease in Man J Ind Med Association 1966; 46 : 649-51.

6. Mehta RB, et al. Hydatid disease in Pondicheri. Ind J Surg 1982; 44 : 48.

7. Borril J, Gemmel MA. An experimental approach to evaluate the potential risk to hydatid disease from inhalation of echinococcus ova. Brit J Surg 1965; 52 : 876-8.

8. Ian AIRD. A companion in surgical studies. 2nd edition 1958:273.

9. Tiwari AK, Tiwari RN. Hydatid disease in Chotanagpur region of South Bihar. Ind J Surg 1988; 50 (1) : 14-18.