Z Pan, W Hunter
echinococcosis, hydatid cyst
Z Pan, W Hunter. Hydatid Cyst Of The Liver: A Case Report And Review Of The Literature. The Internet Journal of Parasitic Diseases. 2006 Volume 2 Number 1.
Hydatid cyst of the liver is caused by a tapeworm,
A 37 year-old Middle-Eastern (Iran) gentleman complained of sharp, right side pain that radiated into his chest. The patient had no history of cardiac disease, and the pain was not associated with cough, wheezing, shortness of breath or hemotysis. CT scan showed two cystic lesions in the liver, one measuring 4.8 cm in the superior right lobe and the other 4.0 cm in the junction of the right and the left lobes. These two cysts were resected completely.
Grossly the cyst wall measures 0.3 cm thick and contains gelatinous yellow soft material without any specific organisms. Microscopically, the cyst wall shows dense fibrous tissue with focal dystrophic calcification (Figure 1A). Sections of the cyst contents reveal granular amorphous material with focal calcification. A hooklet-like structure is identified in the cyst contents in Haematoxylin and Eosin (H.E) slides (Figure 1B) after carefully examining throughout the specimen. The hooklet-shaped structure does not polarize, and it is best seen with the condenser down and with refracted light. Specific stains using Ziehl-Neelsen stain and trichrome stain highlight many similar hooklet-like structures that are stained as purple-blue and pink-red respectively (Figure 1C and 1D).
A very occasional and rare hook-like structure is seen in the cyst and the cyst contents (H.E stain, 40x);
Ziehl-Neelsen stain highlights the hooklet-shaped structures (40x);
Trichrome highlights the hook-shaped structures (40x).
Human echinococcosis is a zoonotic infection caused by the tapeworm of the genus
The incidence cystic echinococcosis in endemic areas ranges from 1-220 cases per 100,000 inhabitants, while the incidence of alveolar echinococcosis ranges from 0.03-1.2 cases per 100,000 inhabitants, making it a much more rare form of echinococcosis. Infestation with
Hydatid cyst disease is due to
Pre-operative diagnosis of hydatid cysts can be made ultrasonically and confirmed by a CT scan. The CT scan has an accuracy of 98% to demonstrate the daughter cysts, and it is the best test to differentiate hydatid cysts from amebic and pyogenic cysts in the liver . A thin rim of calcification delineating a cyst is suggestive of an echinococcal cyst. MRI offers no real advantage over CT scan. Several serological tests can be used for diagnosis, screening, and post-operative follow-up for recurrence. These include the hydatid immunoelectrophoresis, enzyme-linked immunosorbent assay (ELISA), latex agglutination and indirect haemagglutination (IHA) test .
The morphological diagnosis by the pathologist is frequently made by the presence of hydatid elements, especially hooklets. In our case, the hooklets are very difficult to find under transmitted light in H.E slides even by carefully examining through the specimen. However, using either Ziehl-Neelsen stain or trichrome stain, the hooklets are stained purple-blue and pink-red respectively, and many hooklets are easily to identify over the background. Therefore, these two stains offer significant advantage in morphological diagnosis of hydatid cysts, especially very old lesions, where hydatid components may be very difficult to identify.
The treatment of hydatid cyst is principally surgical resection [8,9,10,11,12]. However, pre- and post-operative one-month courses of Albendazole and two weeks of Praziquantel should be considered in order to sterilize the cyst, decrease the chance of anaphylaxis, decrease the tension in the cyst wall, and reduce the recurrence rate post-operatively. To decrease the risk of releasing circulating smaller cysts, hypertonic saline and ethanol are injected into the large cyst 30 minutes prior to surgical removal. In endemic areas, prevention is primarily through prophylactic treatment of dogs with praziquantel to remove the adult tapeworms. Prolonged freezing of meat or fully cooking can kill cysts in tissue.
William J. Hunter, MD Department of Pathology Creighton University Medical Center Omaha, NE 68131 USA TEL: (402) 449-4630 FAX: (402) 449-5252 E-mail: email@example.com