SELECTED STUDIES

Hydatid Cyst: 
Diagnosis & Treatment*

By Prof. Mahmoud Lotfi, MD, FICS

Hydatid cyst is a widespread Zoonotic infection caused by Genus Echinococcus ,which infecting domestic and wild animals(Definitive and Intermediate Hosts) and accidentally Man. Hydatid Cysts are mostly located in the liver, lung, and  in the abdominal cavity mostly in the liver, up to 70 % of cases. To compare E.Multilcularis is more destructive than E.Granulosus, thus diagnosis and treatment are totally different. This disease is, usually, asymptomatic for years even the life time. Until, be discovered by imaging or in laparotomy ,for other reasons.

Clinical Manifestations

Clinical manifestations depends on the location and size. The most presentations in the abdomen are abdominal discomfort and pain, abdominal mass, hepatomegaly, and jaundice. Jaundice is not always due to cyst rupture, but it can be because of external compression of the enlarged cyst, to the main ducts (obstructive jaundice). In the brain, 1 out of 9 are symptomatic. Symptoms are similar to those of other space occupying lesions: Headache, seizure and visual disorder.

Diagnosis:

A high index of suspicious is of almost importance in planning the investigation and final diagnosis of HC. Various sensitive imaging methods and serodiagnostic tests are available for identifying and characterizing hydatid mass lesions. Negative test results do not rule out Echinococcosis. Regardless the location  tests are least sensitive for intact H.C.  

1. Casoni, Weinberg, time being honored, have no place in diagnosis today.

2. Indirect Hemoagglutination, 

3. Indirect Immunoflorescence ,Enzime-linked Immunosorbent Assay (ELIZA) are highly sensitive

4. Counterimmunoelectrophoresis is more sensitive in screening

5. Imaging: Although in the past decade there have been dramatic advances  in organ imaging,plain X-Ray of the abdomen ,lung and bones still has its valuable place

6. We do not use Radionuclide any more because H.C. can be superbly shown by US, specially in solid organs. It shows the location number and complications. Also, it is readily available cost  effective and sensitive imaging  method. But small or deeply situated cysts can be missed. If daughter cysts are not shown to distinguish univesicular HC  from  a simple  cyst , Immunologic tests are coplimentary in establishing the final diagnosis. Also it is one of the  best methods using for  follow-up

7. CT scan: CT is not more sensitive than US. But, it gives better information about the location and depts , of the cyst, daughter cyst, and  exogenous cysts that can be clearly , in intra-abdominal seen. In this case it is more  helpful than US. CT is also essential when laparoscopic approach is going to be performed.

8. MRI does not provide more information than US and CT. But ,for cardio-pericardial HC , it  is the most reliable diagnostic tool.

9. MRCP is one the best  method to detect Biliary Tree problems peri-operatively in complicated H.C.

Management:

Prevention: If control measures are maintained the disease can successfully be eradicated, which is the best way of  treatment. Vaccination of sheep and other intermediate hosts may be possible  in the near future, (Gammell et al 1986).

Medical Therapy:

Until recently, treatment of HC was exclusively in the hands of surgeons. Experience with the benzimidazole presented by Heath ,Crystal & Chevis (1974), and then Bekhti (1977) has gradually established drug therapy as a valid treatment alternative. Mebendazole 40-50 mg /Kg /Day,the first drug be used, has  low absorption low concentration and consequently poor results. Albendazole has a better absorption, acceptable concentration, with scolicidal effects.We use  10-15 mg /kg/day  in divide doses for 3-4 periods of 30 days with  drug free intervals of 14 days. We had good result in prevention  and therapy with this regimen.

Praziquantel is another agent totally different, coumpound, is a rapid scolicidal agent. We use 50mg/kg /day. It is useful for prevention pre-operative and/or post- operative. Combined therapy with albendazole  is advisable, before surgery. Albendazole is currently our choice for treatment of HC. Follow up should be continued for at least 2 yrs.

Surgery:

Surgery is still the procedure of choice.

We should consider the following principals before, during and after surgery:  

1. Peri-operative medication for 14-30 days

2. Prevent spillage

3. Remove all living cyst elements

4. Investigate the cavity carefully  

5. close the defect properly  

6. sterilize cavity

7. Manage the cavity

To inactivate the scolices , 0.5% silver nitrate advocated by  Saidi is the best. But we may use, Saline 30%  Ceterimide 0.5% pure Alcohol, Betadine Hydrogen Peroxide, but never Formalin. None of these agents are harmless, or 100% effective. Specially, in our experience, they do not inactivate  the daughter cysts at all. Before, using this solutions, we have to be sure there is no any biliary communication. Thus, I believe  preventive therapy with albendazole and praziquantel, should be considered before surgery.

As regard the surgical techniques, we used to use Mrsupilization, but now we may use it for very rare special cases. Among the routine procedures, we prefer Omentoplasty, as the procedure of choice, in complicated and uncomplicated cases.

Mahmoud Lotfi, MD, is a professor of surgery and former vice-head in education and research at Tehran Medical Sciences University in Iran. His email is mahmoud_lotfi2002@yahoo.com.

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