Case of the Month- Hydatid Cyst of the Lung

A 28 year old lady presented with the complaints of persistent cough, low grade fever and malaise for 6 months. On investigation she was found to have a cystic lesion in the right upper lobe of the lung abutting the oblique fissure. She also had a cystic mass in the right lobe of the liver. The radiological findings were consistent with the diagnosis of hydatid disease of the lung and the liver.
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Chest X Ray before surgery.

Chest X Ray at initial presentation.

CT images

She was advised surgery which she refused and was sent home on oral albendazole therapy. She returned after one month a repeat chest x-ray showed that the cyst fluid had drained and it was now empty.

She underwent a right thoracotomy. The cyst was located in the right upperlobe abutting the oblique fissure. After isolating the adjoining areas with sponged soaked in hypertonic saline(scolicidal agent), the cyst was incised. The white ectocyst was removed completely (photograph below). On water testing two areas of bronchial leaks were found. They were secured with polypropylene stitches. The cyst cavity was then obliterated with multiple purse string sutures. The chest was then closed.

Removed ectocyst (germinal membrane).

Comment- hydatid disease or Echinococcosis is a zoonotic infection caused by the tapeworm of the Echinococcus species. In humans E.granulosus is the most common. Humans are accidentaly infected by ingesting food contaminated with embyonated cysts. Theoretically any organ may be involved ,bur liver and lung account for nearly 90% of the cases. The symptoms depend on the site involved and are due to pressure or mass effect and cyst complications. Cyst complications include allergic reactions due to leakage and infection.
Diagnosis is usually made by the classic radiological appearance. The indirect haemagglutination test and ELISA have a sensitivity of  90% in hepatic echinococcosis, 40% in pulmonary echinococcosisand are the initial screening tests of choice.

Antibodies to antigen 5 on IE confirm the diagnosis. The historical Casonis intradermal test is no longer used.
The treatment of this condition is surgical. The cyst is aspirated using high suction. the cavity is sterilised using scolicidal agents. Peri and post op Albendazole/Mebendazole therapy is recommended upto 6 months to prevent recurrence.