How Best to Manage Asymptomatic Hepatic Hydatid Cysts?

My patient is a 45-year-old otherwise healthy, asymptomatic woman from Iran in whom a hydatid cyst (Echinococcus granulosus) was incidentally discovered. The immunologically confirmed cyst is located in the left lobe of the liver, and it pushes slightly on the pancreas; its dimensions are 13 3 2.5 cm. Liver enzyme levels are normal. Should this patient be treated with albendazole and surgery or be monitored only?

----- A. Housiar, DO
Irvine, Calif



Hydatid cysts of the liver (also called cystic hepatic echinococcosis) are frequently asymptomatic and are detected only incidentally by radiographic imaging (eg, ultrasonography or CT) (Figure). Symptomatic patients with intact cysts generally have no fever or other systemic signs of infection; instead, they present with abdominal symptoms related to the mass effect caused by the expanding cyst.

Natural course of cystic hepatic echinococcosis. The major risk posed by any hepatic hydatid cyst is that of rupture and leakage of cyst fluid, which can lead to the serious complications of anaphylactic shock and seeding of adjacent structures. The former can be fatal, and the latter is associated with the development of new hydatid cysts at other intraabdominal sites, such as the viscera, omentum, and peritoneum or retroperitoneum.

The host's defenses may eventually calcify small hydatid cysts as part of the healing process-with or even without specific antiparasitic drug therapy. However, larger lesions (greater than 2 cm), even if asymptomatic, should be managed with a combination of medical and surgical approaches.

Treatment of hepatic hydatid cysts. For decades, the recommended treatment for cystic hepatic echinococcosis was open surgical resection of all cysts after meticulous surgical site packing to minimize intraoperative complications. Historically, conventional teaching was never to aspirate a hydatid cyst through the skin. However, the advent of effective antiparasitic chemotherapy for the cestode E granulosus-first mebendazole and later albendazole-dramatically changed the management of such lesions.

Today, the PAIR technique (percutaneous aspiration, injection, and reaspiration), combined with preoperative and postoperative administration of albendazole, is used to manage most hydatid cysts in the liver and elsewhere. A 10-day course of albendazole is given before surgery in an attempt to sterilize the cyst contents. Then, percutaneous aspiration of the cyst is performed, followed by installation of a scolicidal solution, such as hypertonic saline or ethyl alcohol, to kill residual infective scolices and protoscolices within the cyst. After about 30 minutes, the scolicide and the remaining cyst contents are reaspirated. Microscopic examination of cyst contents confirms the parasitic nature of the lesion (which may be suggested by serological tests before the procedure, as in your patient) and the death or viability of hydatid fragments. For large cysts, reinjection of a small amount of scolicide is sometimes performed and the solution is left in place. After PAIR, patients typically continue to receive albendazole for an additional 2 to 4 weeks.

Compared with surgery, the PAIR technique plus chemotherapy is associated with greater clinical and parasitological efficacy; lower rates of morbidity (ie, anaphylaxis, biliary fistula, cyst infection, liver/intra-abdominal abscess, and sepsis), mortality, and disease recurrence; and shorter hospital stays. Minor allergic reactions accompanying PAIR can usually be effectively managed with antihistamines, corticosteroids, and supportive care.

----- Raymond A. Smego, Jr, MD, MPH
Associate Dean for Graduate Medical Education
The Commonwealth Medical College
Scranton, Pa