SUMMARY
Objective: The cardiac hydatid cysts are rare cases, representing 0,5-2% from all human hydatid cysts. They are commonly located in the left or right ventricle and exceptionally in the interventricular septum. Because the symptoms and clinical signs of the cardiac hydatid cysts are non-specific, the diagnosis may be difficult.
Material and Methods: We report an intramyocardial hydatid cyst, diagnosed at Cardiology Center Iasi, with an early history of atypical chest pain, the death producing through anaphylactic sock, secondary to the hydatid cyst endocavitary rupture. The study was made on necropsic specimens, and the diagnosis was established by using routine morphological techniques. 
Results: The gross examination evidentiated an hydatid cyst of about 6 cm in diameter, communicating through a small orifice with the left ventricular cavity and through a slit-like fissure with the right ventricular chamber. The systemic embolism was revealed, only grossly, by the presence of small “hydatid daughters” at the level of the ascending aorta and the pulmonary embolism was confirmed only histologicaly, by the presence of anhiste membrane emboli in the peripheral pulmonary vessels. 
Conclusions: The study revealed the morphological aspect defining hydatid cyst, emphasising the necessity of an early diagnosis due to a high risk of death through complications.
Key words: cardiac hydatid cyst, hydatid daughters, systemic embolism, pulmonary embolism. 
Abbreviations: CHC= cardiac hydatid cyst, LV=left ventricle, RV=right ventricle
 

RESUME
Le but de travail: Les kystes hydatiques cardiaques sont des cases rares qui represante 0,5 – 2 % des toutes les kystes hydatiques humaines. Il sont frequent localisees dans le ventricule gauche ou droit et exceptionellement dans le sept ventriculaire. Parce que les signes cliniques de kyste hydatique sont nespecifiques le diagnostique est difficile.  
Material et methode: Nous rapportons un cas de kyste hydatique intramyocardique diagnostiquee au Centre de Cardiologie Iasi. Il avoit des antecedentes recentes de la duleure thoracique atipique et l’exitus se produit par le choc anaphilactique secundaire a la rupture de kyste hydatique dans la cavitee cardiaque. L’etude a ete fait sur des pieces de la necropsie et le diagnostique a ete etabli par l’utilisation des techniques usuales. 
Resultates: L’examen macroscopique a releve un kyste hydatique de 6 cm diametre qui communiquait par l’intermede d’un oriffice mince avec la cavitee du ventricule gauche et par une fissure avec la cavitee du ventricule droit. L’embolie systemique a ete demontre seulement macroscopique par la presence des vesicule- filles au niveu de l’aorte ascendente et l’embolie pulmonaire a ete mis au evidence seulement histologique par la presence des embolies avec des cuticules acellulaires dans les vaissaux pilmonaires periferiques. 
Conclusion: L’etude a releve les modifications histologiques specifiques de kyste hydatique ce qui impose le diagnostique precoce pour prevenir les graves complications. 
Mots clefs: kyste hydatique cardiaque, hydatique-filles, l’embolie systemique, l’embolie pulmonaire. 
Abbreviations: CHC= kyste hydatique cardiaque, LV= ventricule gauche, RV= ventricule droit.
 

INTRODUCTION 
     Echinococcosis or hydatid disease (HD) consists of cysts due to developing of sheep or attendant dog tapeworm Echinococcus granulosus (Eg). The disease is especially common in sheep-raising areas of South America, Australia and Mediteranian countries. Sporadic cases were reported in the West Europe and North America. Humans become infected when they ingest the tapeworm eggs. The larvae released from eggs penetrate the wall of the gut, enter the bloodstream and disseminate to deep organs where they grow to form hydatid cysts (HCs). The most common sites of HD are the liver (75%), lungs (10%), and skeletal muscle (5%) (1). 
    The cardiovascular location in HD is rare; it is seen in 0.5 to 2% of cases (2). The cardiac involvement may be primitive or secondary. In the first case the embryos may reach the heart on the blood stream after the passing by hepato-pulmonary filter (3). In the second case it may result after the rupture of a hydatid cyst located in the lung, liver, or other adhiacent organs. Cardiac hydatid cyst (CHC) may be localised in different heart sites. The most commonly involved is the myocardium and less frequent are the subendocardial and subepicardial areas (3). In case of myocardial involvement, the HCs are commonly located usually in the left ventricle (LV) and less in the right ventricle (RV) and exceptionally in the interventricular septum. These cysts may rupture into the cardiac cavity or pericardium. The primary pericardial cysts may be rarely found (2).  
    Clinically, the early CHCs are often asymptomatic and discovered incidentally on chest X-ray. Later, CHCs become manifested due to compression on vital structures, sometimes leading to valvular obstruction (Olsen); through endocavitary  rupture may result pulmonary emboli with accompanying pulmonary hypertension, or systemic emboli; rupture of the cyst may be also accompanied by an anaphylactic reaction. Histologically, the cysts evoke firstly an inflamatory reaction and then a strong fibrous reaction, displacing the surrounding myocardial cells. Alive daughter cysts or degenerated ones and calcified cysts are also commonly found (4). The diagnosis of the CHC is suggested by: the presence of a cystic mass in the cardiac area, eosinophilia, the positivity reaction to the skin (Casoni test), and a history of anaphylactic attack (5). The treatment of the ecchinococcal cysts frequently requires careful surgical removal. 
 

MATERIAL AND METHODS 
    A 48 years old female patient suffering of 4 weeks atypical anterior chest pain, and having a CT scan revealing an antero-septal cystic mass, partially adherent from pericardium, died at 9 days after the hospital admission with progressive cardiovascular collapse unresponsive to treatment. The necropsic specimens were fixed in buffered 10% formalin for 12 hours, followed by routine paraffin embedding, cutting (5 mm) and hematoxilin-eosin (HE) and Van Gieson (VG) staining.
 

RESULTS 
     The patient from a rural zone, sheep-raising area, without significant cardiovascular history, presenting clinically an atypical anterior chest pain by only 4 weeks, was admitted for more investigations and cure. The lab tests showed a moderate inflammatory syndrome without eosinophilia. The echocardiography evidentiated a moderate cardiomegaly, explained at CT scan by the presence of a septal cystic mass, partially adherent from the pericardium. The patient died at 9 days from hospital admission through a progressive cardiovascular collapse.
    On gross examination we revealed an unilocular CHC, in an antero-septal location with subepicardial projection, appearing as a fluid and multiple hydatid daughters-filled structure. The CHC, having 6 to 7 cm in diameter, presented an wall composed from a fibrous adventicea, an anhiste and a proligere membranes. The HC had a relative oval LV endocardial opening, of about o.5 cm in diameter, permitting the left endocavitary passing of the hydatid fluid and small hydatid daughters, evidentiated grossly, only at the level of the ascending aorta, as a confirmation of the systemic embolism; adhiacent to this anterior area we also observed an irregular RV endocardial fissure, of about 0.5 cm length, permitting the RV entrance of the hydatid components in the pulmonary circulation, appearance confirmed only histologicaly, demonstrated by the lung presence of the membrane anhiste emboli filling the peripheral pulmonary vessels. 
    The histological specimen examination revealed the well known HC structure, consisting from an hydatid cyst wall composed by an outer non-nuclear laminated layer, with free or attached hydatid daughters projecting into the cyst cavity (Fig. 1), and a cavity containing hydatid sand and a clear fluid.
    Microscopically, the myocardium outside of the hydatid cyst showed the following stratification: a pericystic fibrotic layer infiltrated with chronic inflammation (Fig. 2); myocytic atrophy and diffuse interstitial fibrosis, as signs of chronic ischemia (Fig. 3); on a detailed photograme we observed the fibrotic tissue intermixed with multiple inflammatory cells represented by lymphocytes, macrophages, numerous plasma cells, and few eosinophils (Fig. 4).
   Histologically, the lung revealed different appearances (Fig. 5), such as: small foci of pulmonary emphysema defined by the presence of delicate alveolar walls, some of them ruptured with the formation of large alveolar spaces; multiple peripheral pulmonary emboli, represented by fragments of anhiste membranes filling the peripheral pulmonary arterioles. We didn’t observe microscopically systemic emboli sites.

     
DISCUSSIONS AND CONCLUSIONS
     The cardiovascular involvement in the HD represents a rare location. Virmani (1) showed that two thirds of the human E.g. cysts are found in the liver, 5 to 15% in the lung and the rest in the brain and other organs including heart. Virmani also noted that the CHD is rarely, representing about 1% from all HD. 
    Referring to the cardiac location, we evidentiated the development of the HC into the myocardium with a prominent subepicardial expansion without opening of the CHC into the pericardial sac. Regarding to the cardiac location of the HC, Silverberg (2) observed that over 50 per cent of HCs have intramyocardial sites (usually into the free wall and rarely into the interventricular septum) while an exclusively pericardial HC is exceptionally. The patients with pericardial involvement may present a pericardial inflammation associated with clear serous effusion that may contain hydatid sand and daughters. A late complication of this location includes the fibrinous pericarditis, cardiac tamponade and constrictive pericarditis.  
    Gross examination of the CHC does not differ too much from the other sites. These cysts progressively increasing in size may achieve large diameter dimensions, as in our case, when it had over 6 cm in diameter. The gross HC structure, according with Waller (6), was quite distinctive, having a gelatinous appearance, due to innumerable delicate laminations enclosing a clear fluid and hydatid daughters. Waller considers that are enough six months for developing “hydatid daughters” into  HC.
Histologically, in agreement with Sariola (7), there is a specific HC structure. The cyst wall was composed by an outer opaque, non-nucleated layer and an inner nucleated germinative layer enclosing a clear fluid and hydatid daughters. In our study, as many others pathologists (8, 9), we identified outside of the opaque layer an inflammatory reaction associated with an intense fibroblastic response, resulting a fibrous encapsulation impeding the growing of the larvae; we also observed that the progressive larval development, it permeated the external fibrotic layer, intermixed with adhiacent atrophic myocytes, resulting multiple wall prints, which were more evident grossly. Histologically, we evidentiated the same way of the progression of the HD, repeated of the level of the hydatid daughters. The inner surface of them was covered by minute projections of the germinative layer, which developed central vesicles and thus forming tiny “brood capsules” and sometimes separating from the germinative layer to produce a fine sand-like sediment within hydatid fluid. 
    Clinically, in agreement with Waller (6), the CHC was asymptomatic in the early stages, later the growing of the CHC determining cardiac dysfunction according with affected area. So, in our case, the clinical symptoms of the unilocular HC were derived mainly from its complications. The progressive compression of the myocardium determined the parenchymal atrophy. In time, these chronic ischemic changes were converted in acute ones due to gradual expansion of the cyst, resulting the endocardial necrosis and secondary endocavitary rupture. There were two zones of the HC communications: a relative oval communication crossing the LV endocardium, having about 0.5 cm in diameter, and the other was a slit-like fissure crossing the RV endocardium, having about 0.5 cm length. Silver appreciated that RV-HC develops mainly toward endocardium, while LV-HC develops toward pericardium. In some way, both affirmations were demonstrated in our study, because the CHC with an antero-septal position had a left subepicardial projection and two left and right endocavitary entrances. 
In agreement with Silver (10), we can conclude that: 
    1. The CHC is generally discovered when HC causes complications; the commonest being the anaphylactic shock,  the endocavitary rupture with secondary systemic and pulmonary embolism;
    2. The surgical excision remains the single cure of choice with or without medical treatment. 
 

REFFERENCES 
1. Virmani R. Myocarditis. In: Allen Burke and Renu Virmani. Atlas of Cardiovascular Pathology. Ed. AFIP. Washington DC 1966: 21-47.
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6. Waller BF. Myocardial Disease. In: Waller BF. Pathology of the Heart and great vessels, The Mosby Company, 1998, 235-238.
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10. Silver MD. Myocardial Disease. In: Silver MD. Gotlieb AI Eds. Cardiovascular Pathology. Churcchill Livingstone 2001, 272-273.
 

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