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Echinococcus multilocularis massive pericardial infection: Late and dramatic improvement under albendazole therapy

      To the Editor:
      Echinococcus multilocularis infection usually manifests as a chronic aggressive process of the liver.
      • Vuitton D.A.
      • Pawlowski Z.
      Echinococcosis in humans clinical aspects, diagnosis and treatment.
      We report a case of Echinococcus multilocularis infection of the pericardial cavity that resolved under a 4-year parasitostatic treatment with albendazole.
      A 30-year-old man was admitted in March 1998 because of a pericardial mass. He had never traveled out of France and lived in Paris suburbs. In January 1997, he was referred for basal right lung pain. Blood tests showed a C-reactive protein level of 321 mg/L and a high eosinophil count of 770/mm3. Thoracentesis showed a protein- (60 g/L) and cell-rich (2370 cells/mm3) right pleural effusion with 19% eosinophils. Heart ultrasonography and computed tomographic (CT) scan showed a necrotic pericardial mass (57 × 42 mm) that compressed right cavities. A partial surgical excision of the pericardial mass revealed a granulomatous inflammation with a few giant cells and central noncaseous eosinophil necrosis. Cultures for Mycobacterium tuberculosis were negative; nevertheless, antituberculous treatment was begun in December 1997. In March 1998, clinical examination and a large blood test panel were unrevealing. Serology of echinococcosis, using an E. granulosus antigen, was positive, with one blurred arch on immunoelectrophoresis and an optical density of 0.46 (n <0.18) using enzyme-linked immunosorbent assay (ELISA). Serology using an E. multilocularis (Em) antigen was highly positive, with three thin arches on immunoelectrophoresis and an optical density of 0.4 (n <0.17) using ELISA. A more specific ELISA method showed high levels of anti-Em2 immunoglobulin (Ig) G antibodies. A CT scan (Figure 1, A) showed a growing pericardial mass (10 × 5 × 5 cm). The liver was normal. Antituberculous treatment was then switched for albendazole (800 mg/day). Two years later, the patient was symptom free, but the mass size was unchanged on CT scan. In April 2002, thorax CT scan revealed dramatic improvement (Figure 1, B). A specific anti-E. multilocularis Western blot performed in 2002 showed a significant decrease of specific bands intensity when compared retrospectively with the serum of 1998 (Figure 2). The patient is still followed as an outpatient and treated with albendazole 800 mg/day.
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      Figure 1Thorax computed tomographic scan images. (A) Initial examination in 1998. A large mass of 100 × 50 × 50 mm (arrow) is developed between the diaphragm and the inferior atrioventricular sulcus of the heart. The mass is hypodense, showing a peripheral enhancement and thick septations after contrast. It involves the pericardium and the epicardial fat and the right coronary artery (arrowhead) is seen, adjacent to the mass. (B) Fifth year follow-up in 2003, examination at the same level. A clear reduction of the mass is seen, with two small residual images of 15 mm and 25 mm in diameter.
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      Figure 2Immunoblot analysis of patient’s antibodies. Line 1: serum collected at diagnosis (April 1998); line 2: serum collected 4 years later (November 2002); line 3: positive control (alveolar echinococcosis); line 4: positive control (hydatidosis); line 5: negative control. First serum of the patient presented with a pattern highly specific of alveolar echinococcosis, including characteristic bands at 16 and 18 kDa, which are always lacking in hydatidosis. The second serum, collected after 4 years of treatment, also showed a pattern evocating echinococcosis, but with weaker bands.
      Echinococcosis is caused by E. granulosus (hydatid disease) and E. multilocularis (alveolar echinococcosis).
      • Vuitton D.A.
      • Pawlowski Z.
      Echinococcosis in humans clinical aspects, diagnosis and treatment.
      An infiltrative process of the liver is observed in 96.8% of cases.
      • Kern P.
      • Bardonnet K.
      • Renner E.
      • et al.
      European Echinococcosis registry human alveolar echinococcosis, Europe, 1982-2000.
      Because the mortality rate may reach 90% for untreated cases, alveolar echinococcosis is considered similar to liver malignancies.
      WHO Informal Working Group on Echinococcosis
      Guidelines for treatment of cystic and alveolar echinococcosis in humans.
      Alveolar echinococcosis was considered in our patient because of E. multilocularis infection prevalence in France;
      • Bresson-Hadni S.
      • Vuitton D.A.
      • Bartholomot B.
      • et al.
      A twenty-year history of alveolar echinococcosis analysis of a series of 117 patients from eastern France.
      histological examination of myocardial biopsy showing usual features of E. multilocularis infection; thorax CT scan results; and serum antibodies analysis. The Em2 plus ELISA has a reported sensitivity of 97% and an overall specificity of 99% for the diagnosis of E. multilocularis infection.
      • Gottstein B.
      • Jacquier P.
      • Bresson-Hadni S.
      • Eckert J.
      Improved primary immunodiagnosis of alveolar echinococcosis in humans by an enzyme-linked immunosorbent assay using the Em2plus antigen.
      In our patient, patterns obtained with a Western blot assay using E. multilocularis larval antigen were characteristic of alveolar echinococcosis and clearly distinguishable from a hydatidosis pattern (Figure 2).
      • Liance M.
      • Janin V.
      • Bresson-Hadni S.
      • Vuitton D.A.
      • Houin R.
      • Piarroux R.
      Immunodiagnosis of Echinococcus infections confirmatory testing and species differentiation by a new commercial Western Blot.
      Apparent absence of hepatic lesion in our patient is unusual and might be due to an initial location at the liver dome that made the metacestode grow only towards the diaphragm and the pericardium or due to a primitive pericardial location. E. multilocularis heart involvement appears exceedingly rare. In a patient with hepatic alveolar echinococcosis, pulmonary embolism was due to a right-heart parasitic clot that could be removed surgically.
      • Etievent J.P.
      • Vuitton D.
      • Allemand H.
      • Weill F.
      • Gandjbakhch I.
      • Miguet J.P.
      Pulmonary embolism from a parasitic cardiac clot secondary to hepatic alveolar echinococcosis.
      To our knowledge, no case of isolated pericardial or myocardial involvement due to E. multilocularis has been reported.
      In conclusion, E. multilocularis may infect the pericardial cavity without disclosable liver involvement. Sensitivity of the parasitic lesions to albendazole in this location suggests that chemotherapy should be considered when surgery is impossible or at risk. Because disease improvement may occur very late, albendazole should be pursued even when no change is disclosed over the first years of treatment. Despite objective mass regression and encouraging immunological changes, the decision to withdraw albendazole remains difficult.
      • Ma L.
      • Ito A.
      • Liu Y.H.
      • et al.
      Alveolar echinococcosis Em2plus-ELISA and Em18-western-blots for follow-up after treatment with albendazole.
      • Bresson-Hadni S.
      • Beurton I.
      • Bartholomot B.
      • et al.
      Alveolar echinococcosis.
      Appropriate tools are still needed to measure the viability of the parasitic lesions in order to avoid an indefinite treatment in such patients.

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