Some rare presentations of hydatid cysts: two case reports
© Zaidi; licensee BioMed Central Ltd. 2009
Received: 29 October 2008
Accepted: 18 January 2009
Published: 18 January 2009
Hydatid disease is a considerable health problem worldwide. Two case reports of relatively uncommon presentations of the disease are presented.
The first case is that of a 25 years old female from region of Afghanistan that borders Pakistan's Baluchistan province. She presented with cough, hemoptysis and left hypochondrium pain due to concurrent involvement of the right lung and the spleen due to hydatid disease, whilst sparing the liver.
The second case is that of a 32 years male from the same region of Afghanistan as above. He presented with upper abdominal discomfort, postprandial vomiting and jaundice due to a hydatid cyst involving the head of the pancreas only.
Hydatid disease, caused by the larval stage of the parasite Echinococcus, is a considerable health problem worldwide. E. granulosus accounts for the majority of the cases whilst E multilocularis and E vogeli are rare. Humans happen to be accidental or incidental intermediate host and, as far as the parasite is concerned, a dead end. Hydatid disease can involve any organ. The liver is the most common organ involved and, together with the lungs accounts for 90% of the cases. Other sites of involvement are muscles (5%), bones (3%), kidneys (2%), brain (1%), and spleen (1%) . Pancreas is affected in 0.25–0.75% of adult cases, the mode of infestation being hematogenous, via pancreatic or bile duct as well as lymphatic .
This paper emphasizes the fact that hydatid disease should be suspected in cystic lesions affecting any organ in the body, especially in endemic areas of the world.
The adult worm resides in the intestine of its definitive host, the dog and related carnivores. The eggs passed in the feces are ingested by grazing sheep, goats and cattle. The eggs hatch, penetrate the host's intestinal wall and reach the liver through the portal vein. From there they are distributed by the bloodstream to the lungs and other organ systems. Eggs become transformed to the larval stage, the scolex, which can continue to multiply asexually indefinitely within the hydatid cyst. The natural cycle is completed when a hydatid cyst is devoured by a canine host. The multiplication of the larval scolices results in a slow but steady physical enlargement of the cystic colony. Since the enlargement is very gradual the patient's symptoms are rarely acute. The cyst consists of three layers. The outer most, or the pericyst, is an adventitial layer of host origin. The middle layer is the outer chitinous covering of the parasite or the laminated membrane. The innermost germinal layer gives rise to the scolices .
The usual mode of acquiring the infection is through ingestion of contaminated vegetables. Symptoms are caused by pressure effects but are vague initially. Pain, cough, low-grade fever, and the sensation of abdominal fullness are common features. As the cyst grows, the symptoms become more specific depending on the specific structures involved. Secondary complications include of infection or rupture of the cyst .
Theoretically no organ is immune form hydatid disease. When the relatively rare sites are involved, the mainstay of diagnosis remains a high index of suspicion supplemented by radiologic and hydatid serology . Although eosinophilia is expected in patients with parasitic infestations, it has been reported to be present in only 25% of cases of hydatid disease . Surgical removal remains the main form of definitive treatment. Chemotherapy is indicated in inoperable cases because of location, multiplicity of organ involvement or in patients with serious medical conditions .
Unfortunately, the patients could not be traced to obtain written informed consent. I believe that this case report contains a worthwhile clinical lesson that could not be made as effectively in any other way. I expect that a reasonable person would not object to the publication since every effort has been made so that patient remains anonymous.
I would like to acknowledge the support of the radiology unit and the pathology laboratory of Combined Military Hospital Quetta for their help in preoperative investigation of the cases and the postoperative confirmation of the diagnoses by the histopathologist, Dr Iqbal Khan.
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