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8,201 | salty. Mass effects can be noted in the brain and bone. Serious complications result from compression of adjacent structures or spillage of cyst contents. Type I hypersensitivity reactions, including anaphylaxis, can occur with spontaneous spillage or with cyst rupture from trauma or during surgery. Fluid from ruptured lung cysts can cause hypersensitivity pneumonitis. Spillage of fluid from a viable cyst can cause catastrophic long term complications. Each pro toscolex can form a new cyst and fill up the abdominal cavity or other spaces, including the pleura, biliary tree, and pelvis. Jaundice from cys tic hydatid disease is rare. Alveolar hydatid disease is sometimes diagnosed incidentally, but often the proliferating mass compromises the biliary system andor hepatic tissue, causing progressive obstructive jaundice and hepatic failure. Symptoms also occur from expansion of extrahepatic foci. DIAGNOSIS Ultrasonography is the most valuable tool for both the diagno sis and treatment of cystic echinococcosis of the liver. The World Health Organization (WHO) standardized ultrasound criteria for classification of liver cystic echinococcosis have been shown to be reliable with excellent interintraobserver reliability. Ultrasonogra phy staging has a direct use in defining optimal therapy with cystic echinococcosis types 1 and type 2 (CE1 and CE2) cysts considered fully active, CE3a and CE3b transitional, and CE4 and CE5 inac tive (Fig. 350.2). Chest radiographs frequently reveal characteristic rounded masses in lung cystic echinococcosis (Fig. 350.3). Alveolar disease resembles a diffuse solid tumor. CT findings are similar to those of ultrasonography and may at times be useful in distinguish ing alveolar from cystic echinococcosis in geographic regions where both occur (Fig. 350.4). CT or MRI is also important in planning a surgical intervention. Serologic studies are used to confirm the diagnosis of cystic echi nococcosis, although some children with active cystic echinococcosis do not have detectable levels of specific antibody. Cross reaction with other helminths is possible when using crude hydatid fluid antigens for the serology. The sensitivity and specificity of serologic assays to diag nose cystic echinococcosis vary significantly by location of the cyst, stage, and treatment status. The enzyme linked immunosorbent assay performs better than Western blot and indirect hemagglutination with the highest sensitivity for CE2, CE3, and CE1 cysts (6499) com pared to CE4 and CE5 (5191). The sensitivity is higher for hepatic or bone disease, but the false negative rate may be 50 with pulmonary or central nervous system (CNS) infection. Differential Diagnosis Benign hepatic cysts are common but can be distinguished from cys tic echinococcosis by the absence of a distinct three layer wall, inter nal membranes, and hydatid sand. The density of bacterial hepatic abscesses is distinct from the watery cystic fluid characteristic of E. granulosus infection, but Echinococcus cysts may also be complicated CE1 (type I) CE2 (type II) CE3 (type III) CE4 (type IV) CE5 (type V) Fluid collection (hyaline) Multivescular Fluid collection with split wall Heterogeneous pattern Calcified Fig. 350.2 Ultrasound classification of cystic echinococcosis (CE) cysts. The WHO informal working group on echinococcosis classifica tion differs from that of |
8,202 | Gharbi and colleagues by the addition of a cystic lesion (CL) stage (undifferentiated) (not shown) and by revers ing the order of CE types 2 and 3. CE3 transitional cysts may be differ entiated into CE3a (with detached endocyst) and CE3b (predominantly solid with daughter vesicles). CE1 and CE3a are early stage cysts and CE4 and CE5 late stage cysts. (From McManus DP, Gray DJ, Zhang W, Yang Y. Diagnosis, treatment, and management of echinococcosis. BMJ. 2012;344:e3866. Fig 4.) Downloaded for mohamed ahmed (dr.mms2020gmail.com) at University of Southern California from ClinicalKey.com by Elsevier on April 21, 2024. For personal use only. No other uses without permission. Copyright 2024. Elsevier Inc. All rights reserved. 2222 Part XV u Infectious Diseases by secondary bacterial infection. Alveolar echinococcosis is often con fused with hepatoma or metastatic tumor. TREATMENT Management of cystic echinococcosis should be individualized and guided by disease stage and location. Approaches range from surgi cal resection for disease that tends to respond poorly to drugs and complicated cysts to watchful waiting for cysts that have already degenerated. For CE1 or CE3a cysts (see Fig. 350.2) that are 5 cm in diameter, albendazole chemotherapy alone (15 mgkgday orally divided twice daily for 1 6 months; maximum 800 mgday) may result in a high rate of cure. Adverse effects include occasional alo pecia, mild gastrointestinal disturbance, and elevated transaminases on prolonged use. Because of leukopenia, the U.S. Food and Drug Administration (FDA) recommends that blood counts be moni tored at the beginning and every 2 weeks during the first 3 months of therapy and monthly afterward. Medical treatment with albendazole may also be used for cysts that are not suitable for interventions such as PAIR (percutaneous, aspiration, instillation, and reaspiration) or surgery, but response rates are low. For larger CE1 and CE3a lesions, ultrasound or CT guided PAIR is the preferred therapy. Compared with surgical treatment alone, PAIR plus albendazole results in similar cyst disappearance with fewer adverse events and fewer days in the hospital. Spillage with PAIR is uncommon, but prophylactic albendazole therapy is rou tinely administered at least 1 week before PAIR and 1 month afterward. PAIR is contraindicated in pregnancy and for bile stained cysts, which may indicate the presence of a biliary fistula. The scolicidal agents instilled during PAIR may increase risk for biliary complications in these patients. Surgery with albendazole treatment is the recommended approach for CE2 and CE3b cysts of the liver. In experienced centers, cysts with thick internal septation (CE2) can be managed using a trocar to break up the membranes and external drainage. CE4 and CE5 cysts do not require immedi ate interventions and are followed ultrasonographically for signs of reactivation. Surgery is the treatment of choice for complicated cysts, includ ing ruptured cysts, cysts communicating with the biliary tract, large pulmonary cysts, or cysts of the CNS or bones. Small thoracic cysts may resolve with albendazole, but most cysts require operative removal. For conventional surgery, the inner cyst wall (only laminate and germinal layers |
8,203 | are of parasite origin) can be easily peeled from the fibrous layer, although some studies suggest that removal of the whole capsule has a better outcome in terms of recurrent disease. Consider able care must be taken to avoid spillage of cyst contents, and surgi cal drapes should be soaked in hypertonic saline because cyst fluid contains viable protoscoleces, each capable of producing secondary cysts. An additional risk is anaphylaxis because of spilled cyst fluid, making it useful to employ a surgeon experienced in this surgery. For hepatic cysts, patients should begin therapy with albendazole (ide ally in combination with praziquantel) for several days to weeks pre operatively. Antiparasitic drugs should be continued for 4 12 weeks postoperatively. Alveolar hydatidosis frequently requires radical surgery, includ ing partial hepatectomy, lobectomy, or liver transplantation. Medical therapy with albendazole should be continued for at least 2 years after presumably curative surgery. In patients who are not opera tive candidates or whose lesions are not amenable to surgical cure, albendazole long term suppressive therapy should be used to slow the progression, but the infection generally recurs if albendazole is stopped. PROGNOSIS Factors predictive of success with chemotherapy are age of the cyst (2 years), low internal complexity of the cyst, and small size. The site of the cyst is not important, although cysts in bone respond poorly. For alveolar echinococcosis, if surgical removal is unsuccessful, the average mortality is 92 by 10 years after diagnosis. PREVENTION Important measures to interrupt transmission include thorough hand washing, avoiding contact with dogs in endemic areas, and boiling or filtering water when camping. Strict procedures for proper disposal of refuse from slaughterhouses must be instituted and followed so that dogs and wild carnivores do not have access to entrails. Other useful measures are control or treatment of the feral dog population and regu lar praziquantel treatment of pets and working dogs in endemic areas. Vaccines have been developed to prevent infection in grazing animals but are not widely used. Visit Elsevier eBooks at eBooks.Health.Elsevier.com for Bibliography. Fig. 350.3 Serial chest radiographs of bilateral hydatid cysts. After 2 months of albendazole therapy, sud den rupture of the right cyst was as sociated with massive aspiration and acute respiratory distress. Mar5 Apr16 Apr27 May17 Jun7 Jun21 Fig. 350.4 Liver cystic echinococcosis (hydatid disease). Abdominal CT revealed hepatomegaly and multiple (20) liver cysts. (From Ben Shimol S, Zelcer I. Liver hydatid cysts. J Pediatr. 2013;163:1792.) Downloaded for mohamed ahmed (dr.mms2020gmail.com) at University of Southern California from ClinicalKey.com by Elsevier on April 21, 2024. For personal use only. No other uses without permission. Copyright 2024. Elsevier Inc. All rights reserved. |
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