Introduction
Pulmonary hydatid cyst is a rare cause of pneumothorax with the incidence of simple pneumothorax in the paediatric population as a result of pulmonary hydatidosis is around 2.4 to 6.2% of the patients. Due to the presence of chest xray findings, it has the potential of being misdiagnosed as a case of tubercular pleural effusion or empyema. Pulmonary hydatid cyst (PHC) may rupture into the pleural cavity or bronchus. In such cases, PHC may be misdiagnosed with other common pulmonary diseases like tuberculosis and thus patients may not be receiving appropriate treatment. For example, misdiagnoses of PHC may even lead to major lung resection or pneumonectomy.
Case History
We present a case of a 15 year old male who presented to the Respiratory Medicine OPD in AVBRH, Sawangi, Wardha in view of possible surgical intervention and Pulmonologist opinion with chief complaints of fever, breathlessness, right sided chest pain and history of loss of weight and appetite. The initial chest x ray was done which was suggestive of hydropneumothorax and ICD tube insertion was done after which approximately 500ml of yellowish purulent pleural fluid was drained along with air removed. The patient was initially suspected to be suffering from tubercular pleural effusion and was started on AKT from outside. His blood investigations were normal and pleural fluid analysis revealed exudative effusion by Lights criteria, pleural fluid ADA levels were 150 and culture/sensitivity revealed no growth, pleural fluid cytology revealed empyema like nature of effusion with pleural fluid TLC/DLC suggestive of lymphocytic effusion, pleural fluid AFB and CBNAAT were negative for mycobacterium tuberculosis. The patients Sputum for AFB and CBNAAT were also negative. The patient had significant history of contact with dogs and cattle as the family was in the dairy business and hence to investigate further Echinococcus IgG Antibody ELISA was sent which came to be positive (Value- 0.88- Reference values >0.5- Positive) which confirmed the diagnosis of pulmonary hydatidosis.
General examination
On examination, the patient was afebrile, PR- 110/min, RR- 24/min, BP- 110/60 mm Hg, Spo2- 98% on room air, pallor/icterus/cyanosis and clubbing was absent. There was no palpable lymphadenopathy present.
On Respiratory examination
On Inspection- Chest wall bilaterally symmetrical, trachea appears central in position, On Palpation- Trachea central in position, no deviation noted, On Percussion- Right sided dull notes heard, On Auscultation- Right sided decreased breath sounds, right sided succussion splash was heard.
Other systems
Cardiovascular system-Heart sounds normal, no murmurs heard, Gastrointestinal system- P/A soft, non-tender, no hepatosplenomegaly, Central Nervous system- No focal neurological deficit noted, all reflexes normal
Provisional diagnosis
On the basis of history and clinical examination, a provisional diagnosis of right sided pyopneumothorax was made.
Routine investigations
The patients routine blood investigations were within normal limits
After much diagnostic deliberations, pulmonary hydatidosis was considered as a possible diagnosis and the patients Echinococcus IgG Antibody ELISA was sent which came to be positive (Value- 0.88- Reference values >0.5- Positive) and the patient was started on Tab Albendazole 200mg BD for 3 months. The patient was later discharged after 1 month after removal of ICD tube and was advised to continue anti-echinococcal therapy for 3 months and regular reviews every month in the OPD. His serial chvest x rays were done at every OPD visit, which clearly showed resolution of the pleural effusion and consolidation.
Discussion
Hydatid cyst is a parasitic infection caused by the larval form of Echinococcus granulosis complex, E. multilocularis or E. Vogeli.1 Canines are the definitive hosts and humans are the accidental hosts and infection is acquired after consumption of food contaminated with eggs.2 E. granulosus causes cystic echinococcosis and is the most common species to cause the human disease. Although E. multilocularis is rare, it is the most virulent species and causes alveolar echinococcosis. E. vogeli and E.oligarthrus cause polycystic echinococcosis.2
Hydatid disease involves the lungs by various mechanisms. Humans acquire the infection by ingestion of eggs mixed with uncooked or contaminated food, drinking water or direct contact with animals. Gastric and enteric digestion of eggs facilitates the release of embryos. Embryos subsequently attach to the duodenal or jejunal wall by their hooklets and penetrate the intestinal wall after which they reach the liver via the portal circulation. Most of the embryos are stuck in the liver sinusoids but embryos with diameters less than 0.3 mm may pass through the hepatic sinusoids and through the hepatic vein and IVC, enter the right heart and finally settle in the lungs. Embryos can also enter the thoracic duct via lymphatics of the small intestine and then through the IJV enter the right side of the heart and finally the lungs.3, 4, 5
The most common sites of these cysts are the liver and the lungs. Pulmonary cysts can rupture into the mediastinum, bronchial tree or peritoneal cavity and can present with cough, abdominal pain, hemoptysis or chest pain.
Rupture is the most frequent complication of pulmonary hydatid disease occurring in 49% patients.1 The cyst may rupture intrabronchially or into the pleural cavity.6
Surgical intervention is the treatment of choice in selected patients.7 Medical therapy for pulmonary hydatid cyst includes benzimidazoles group of drugs (mebendazole, albendazole). Indications for chemotherapy includes smaller cysts and patients with contraindications for surgery. Albendazole is preferred as it has better bioavailability, requires a minimum contact period of 11 days to have a significant response and should be given for a minimum period of 3-6 months. Continuous therapy is more efficacious as it achieves higher drug levels on a sustained basis and do not allow the metacestodes to gradually recover.
Conclusion
Hydatid cysts in lung are common in endemic area. In the present report, we described details of ruptured pulmonary hydatid cyst in a boy with fever and breathlessness, as the most prominent symptoms. The disease was misdiagnosed clinically, as pulmonary tuberculosis but hydatid serology gave us the diagnosis of pulmonary hydatidosis in this case. After definitive diagnosis, the patient was given anti-echinococcal therapy with Tab Albendazole for 3 months. Patient was discharged with good and stable vital signs. This report emphasizes that the ruptured Pulmonary hydatid cyst should be considered in the differential diagnosis of tuberculosis especially in endemic areas for both infections.
