Discussion:
Hydatic cysts of the heart are extremely rare with an incidence of 0.02-2% and these cysts are barely affect pulmonary arteries.1 Despite being rare, the sequences of pulmonary artery involvement such a pulmonary embolism a pulmonary hypertension, rupture and anaphylaxis or cardiac arrest are life-threatening.3 Several explanation has been described to contribute to the involvement of pulmonary artries: 1.migration of the larvae into the artery wall through “vasa vasarum”, 2.larvae entering the lumen as a result of direct damage from lung parenchyma, 3.blood dissemination through liver or other organs.
H Alper et al. reported a patient with recurrent hydatic cysts involving several organs that undergone several operations. The patient’s manifestation was chronic dyspnea that later was diagnosed via MR and CT-scan as occlusion of pulmonary artery due to rupture of an intramural cyst and thrombosis formation in the lumen; The thrombosis was removed by surgical intervention.1 Another possible mechanism of thrombosis is the rupture of cysts locatedin the right heart chamber.4 Arwa et al. reported a 86-year-old female with previous liver hydatic cyst; Four years later the patient presented with productive cough and dyspnea. The radiologic findings on MRI and CT demonstrated several multiseptate cysts in the lumen of right pulmonary artery besides several primary cysts in the lung parenchyma.5 These cases showed the presence of secondary hydatic lesion in the lumen as a result of simultaneous cysts in other primary organs. Only Aysegul S et al. reported an intra-luminal cyst with obstructive effect on left pulmonary artery and its branches found onendobronchial US investigation which seemed to be a primary cyst.3
Diagnosis of hydatic cysts is based on radiologic and serologic findings.4 Ultrasonography, plain radiographs, MRIs and CT-scans or a combination of these methods are used based on the clinical situation. Magnetic resonance features of hydatic cysts on T2 images include spherical shape, with hyposignal rim on the outside (host reaction) and central signal similar to cerebrospinal fluid.1 Computed tomography studies also show cysts fluid attenuation with defined borders and enhanced contrast on the surrounding tissue.6
Symptoms of primary lung cysts might remain silent for years and the cysts might be the incidental findings of radiographic investigations. Symptomatic intact cysts in the lung parenchyma might represent with cough, hemoptysis and chest discomfort.7 Due to cyst’s slow growth and formation of collateral blood perfusion, hydatic cysts in the pulmonary artery remain asymptomatic until obstruction occurs—that obstruction could be due to mass effect or rupture and subsequent thrombosis.5, 8 The decrease in the pulmonary flow due to obstruction or mass effect on bronchi explains the dyspnea.3 Regarding to the current COVID-19, our case was initially misdiagnosed as SARS-COV2 infection. Several factor led to inaccurate initial COVID-19 diagnosis like the pandemic precautions, lack of previous hydatic cyst history, shorter duration of symptoms and clear initial assessments in the first hospital. However, negative RT-PCR and CT-scan findings ruled out COVID-19 infection.
Lack of sufficient evidence and standandardized protocols limits the options of treatment. It is suggested that the surgical removal is treatment of choice in cases with life threatening obstruction of vital vessels. 1, 5, 9
The hydatic cysts of the pulmonary artery are rare—but life-threatening—and limited to case reports. Most of these cysts are secondary to cysts in the lung or the liver and found in the intramural or luminal space. In this case the patient with no history of hydatic cysts in the lung parenchymarepresented symptoms such as dyspnea and shortness of breath. Regarding to the pandemic and symptoms that mimicked COVID-19, the patient was misdiagnosed as COVID-19 infection. Our report shows that primary hydatic cyst with mass effect in the extra luminal surrounding of pulmonary artery is a possible diagnosis that should be considered and investigated through radiographic evaluations. The treatment choice is made based on patient situation to relieve symptoms which in this case were successful surgical removal.