Infection with the larval form of Echinococcus multilocularis causes alveolar echinococcosis (AE). The infection behaves as a slow-growing malignant tumor. Initially, it is located in the liver and then may spread to any other organ through metastases. Without appropriate therapeutic management, the infection is lethal.
Echinococci are platyhelminths of the cestode genus. The parasitic cycle of the organism involves definitive hosts and intermediate hosts, each harboring different stages of the parasite life cycle.
Although many infections are acquired during childhood, clinical signs may not appear for years, except when cysts are in vital organs. Symptoms and signs may resemble those of a space-occupying tumor.
Liver cysts eventually cause abdominal pain or a palpable mass. Jaundice may occur if the bile duct is obstructed. Rupture into the bile duct, peritoneal cavity, or lung may cause fever, urticaria, or a serious anaphylactic reaction.
Pulmonary cysts can rupture, causing cough, chest pain, and hemoptysis.
Surgical removal or percutaneous aspiration followed by instillation of a scolicidal agent and reaspiration
Sometimes albendazoleTreatment varies depending on the type, location, and size of the cyst and on complications. Surgery, sometimes via laparoscopy, can be curative. Albendazole is often given before surgery to prevent metastatic infections that can occur if cyst contents spill during the procedure. In some centers, percutaneous aspiration under CT guidance is done, followed by instillation of a scolicidal agent (eg, hypertonic saline) and reaspiration (PAIR [percutaneous aspiration-injection-reaspiration]).
Pearls & Pitfalls
Take care to avoid leakage of cyst contents during aspiration or surgery because metastatic infection can occur.
For E. granulosis, albendazole 400 mg po bid for 1 to 6 mo (7.5 mg/kg bid in children up to a maximum of 400 mg bid) is curative in 30 to 40% of patients and can be used to suppress growth in inoperable cases.
Prognosis for patients with E. multilocularis infection is poor unless the entire larval mass can be removed. Surgery is indicated if it is feasible, which depends on the size, location, and manifestations of the lesion. Albendazole in the above doses can suppress growth of inoperable lesions. Liver transplantation has been lifesaving in a few patients.