INTRODUCTION

A 36-year-old man presented with cough since 7 daysassociated with minimal mucoid expectoration. He alsohad left sided chest pain and high-grade intermittentfever since 3 days. He was detected to have retroviralinfection 6 months back and had 2 prior episodes ofrespiratory infections, which settled to local treatment.He was a non-smoker, but had a past history of high-risk sexual behavior. A labourer by occupation, he hadnoticed mild wheezing in the last fortnight, but had noprior history of asthma. There was no history of reducedweight, appetite or other constitutional symptoms.Clinical examination revealed an averagely built andnourished man with normal vital parameters and arespiratory rate of 20 per minute. There were scatteredcrackles bilaterally and reduced breath sounds withincreased vocal resonance in the left inframammary andinfrascapular areas suggestive of left lower lobeconsolidation.

A chest roentgenogram revealed bilateral lower zoneand parahilar infiltrates which were extensive ascompared to the clinical signs (Fig. 1). Blood counts werenormal and the absolute CD4 count of the patient was found to be 112 cells/cu mm. Arterial blood gas analysisdid not reveal hypoxia, but he had mild compensatedrespiratory alkalosis. The patient was started onintravenous cefotaxime and oral doxycycline to covergram positive as well as atypical organisms andprophylactic cotrimoxazole in view of the low CD4counts. He had a normal ESR (12mm) and sputum foracid-fast bacilli (AFB) was negative. Sputumexamination revealed gram positive and negative mixedinfection with adequate sensitivity to the therapy alreadystarted.

Patient’s symptoms subsided and a review chest filmafter 2 weeks revealed resolution of the parenchymalopacities, but two cavities were seen bilaterally in thesame areas (Fig 2). A repeat blood count now revealedeosinophilia of 12% with absolute eosinophil count being840-cells/cu mm. A CT scan of the thorax, revealed twowell-defined thick walled cavities with air fluid levels(Fig 3), in the lower lobes of both lungs with detachedmembranes floating on the fluid in the right-sided cavity,(Fig 4) suggestive of ruptured hydatid cyst.

*Ex-Lecturer; **Ex-Hon. Asst. Professor, ***Residents;Department of Medicine; +Professor and Head, Departmentof Chest Disease; Grant Medical College and Sir J.J. Group ofHospitals, Mumbai, India.Received :10.12.2004; Revised : 1.4.2005; Accepted :2.5.2005

Fig. 2 : Chest film PA view suggestive of two cavities, one in rightlower lobe and other in left lower lobe with resolution of earlierinfiltrates.	Fig 4 : CT scan of thorax showing the torn germinal layer in theright hydatid cyst: the ‘water-lily sign.’
Fig. 1 : Chest film PA view showing bilateral infiltrates atpresentation.	Fig 3 : CT scan of thorax showing the ruptured hydatid cysts withair fluid level on the left side.

An ultrasound of the abdomen did not reveal anyhydatid cysts in the liver. The patient was started onanti-retroviral therapy with lamuvudine, stavudine andeffavirenz and surgery was advised for the hydatid cysts.However the patient was not willing for surgery. Hencehe was started on albendazole at a dose of 10 mg/kg/day for 28 days. Being symptomatically better, he insistedon discharge and was follow-up regularly.

DISCUSSION

The lung is involved in 2 forms of human hydatidosiscaused by the cystic larval stage of the tapeworm,Echinococcus. Cystic hydatid disease is caused byEchinococcus granulosus and alveolar hydatid diseaseby Echinococcus multi-locularis.3 65% to 70% hydatidcysts occur in liver and 15 to 30% in lungs while 5-13%patients have involvement of both organs.4 Pulmonaryhydatid cysts are characteristically solitary and three-fourths of patient’s cysts are in one lobe, more often lowerlobes, posterior more than anterior and more common on the right. 4 Our patient was having bilateral hydatidcysts, which is seen in 6 – 10 % of patients. 1, 2

Cough and chest pain are the commonest symptoms,1 and clinical signs are rarely definitive except for anoccasional fluid thrill in very large cysts. 3 There areoccasional case reports of pulmonary hydatid cystspresenting as non-resolving pneumonia, especiallywhen the cysts are ruptured or infected as was in ourcase. 5 Radiology remains the mainstay of diagnosis,being 98-100% accurate in most cases.3

Our patient had underlying retroviral disease andtherefore the commonest differentials of bilateral lowerzone and parahilar pulmonary infiltrates weretuberculosis or pneumocystis carinii (PCP). However theshort history and absence of constitutional features fortuberculosis and lack of respiratory distress, hypoxia ortoxic appearance and leukocytosis made PCP orbacterial infection an unlikely cause of this bilateralpneumonitis with cavitations. The CT scan of the thoraxunexpectedly revealed ruptured hydatid cysts.

Retrospectively however, the eosinophilia, the recenthistory of mild wheezing and the radiographic changescould be explained on the basis of asymptomatic hydatidcysts, which got secondarily infected and ruptured,thereby manifesting clinically. Treating thesuperimposed infection cleared the infiltrates on theearlier chest film and the cysts could now be visualized(Fig. 2 - arrows); contrary to the impression ofpneumonia with secondary cavitations obtainedinitially.

Within the lung the cyst ruptures in two ways: (1)rupture through pericysts only; and (2) rupture ofpericysts, exocysts, and endocysts, the contents beingexpelled in airways. When there is dissection of airbetween the pericyst and parasitic membrane, usuallydue to erosion of a bronchiole by an expanding cyst, itpresents radiologically as an ‘Air-Bubble’ sign. Howeverwhen the entire cyst ruptures, the ruptured pericyst membranes float on the fluid in cysts and give rise to“water lily sign”or “sign of camalotte”, 6 classically seenin our patient’s scan on the right side (Fig 4- arrow).

Though aggressive course of liver hydatidosis withearly manifestation as well as disseminated pulmonaryhydatid cysts have been described in patients withacquired immunodeficiency syndrome (AIDS),7,8 ourpatient remained asymptomatic and manifested onlywith secondary infection masquerading as pneumoniawith subsequent cavitation. The manifestations ofanaphylaxis that typically occur with rupture were alsosubdued probably due to the poor immune response.

Surgery is the treatment of choice for pulmonaryhydatid cysts and medical treatment is beneficial in caseswhich are inoperable or when patients do not consentfor surgery. Albendazole is recommended at doses of10-15 mg/kg/day for 4 weeks separated by 14-dayintervals for 2 or more courses. However proteaseinhibitors and benzimidazoles interfere stongly at theCYP3A4-level. Hence very low doses of albendazole/mebendazole achieve sufficient therapeutic levels in HIVpatients taking protease inhibitors.9

Thus pulmonary hydatid cysts, though uncommonbilaterally, can present as pulmonary infiltratesespecially with secondary infection, in Indian patientsmore so in those with AIDS. This case highlights theimportance of clinico-radiological correlation in medicaldiagnosis.

We would like to acknowledge Dr. AA Chowdhury,Professor and Head, Department of Medicine, Grant Medical College and Sir J.J. Group of Hospitals, Mumbai,Dr. PH Shingare, Dean, Grant Medical College and SirJ.J. Group of Hospitals, Mumbai for allowing us to publishthe case.

REFERENCES

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2.Biswas B, Ghosh D, Bhattacharjee R, Patra A, Basuthakur S,Basu R. One stage bilateral thoracotomy for hydatid cysts ofboth lungs. Ind J Thorac Cardiovasc Surg 2004;20:126–8.

3.Lahiri K. Parasitic infections of the respiratory tract (diagnosisand management). J Postgrad Med 1993;39:144-8.

4.Jerray M, Benzarti M, Garrouch A, et al. Hydatid disease oflung : study of 386 cases. Am Rev Respi Dis 1992;146:185-9.

5.Koksal D, Altinok T, Kocaman Y, Tastepe I, Ozkara S.Bronchoscopic diagnosis of ruptured pulmonary hydatidcyst presenting as nonresolving pneumonia: report of twopatients. Lung 2004;182:363-8.

6.Kervancioðlu R, Bayram M, Elbeyli L. CT findings inpulmonary hydatid disease. Acta Radiol 1999;40:510-4.

7.Kakrani AL, Chowdhary VR, Bapat VM. Disseminatedpulmonary hydatid disease presenting as multiple cannonball shadows in human immunodeficiency virus infection. JAssoc Physicians India 2000;48:1208-9.

8.Sailer M, Soelder B, Allerberger F, Zaknun D, Feichtinger H,Gottstein B. Alveolar echinococcosis of the liver in a six-year-old girl with acquired immunodeficiency syndrome. JPediatr 1997;130:320-3.

9.Zingg W, Renner-Schneiter EC, Pauli-Magnus C, Renner EL,van Overbeck J, Schlapfer E et al. Alveolar
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