Discussion

Eosinophilic granulomatosis polyangiitis is the rarest of vasculitis in children. There are three paediatric series but each have less than 15 cases. ^{Reference Fina, Dubus and Tran1−Reference Gendelman, Zeft and Spalding3} To our knowledge, less than 100 paediatric cases have been reported. ^{Reference Fina, Dubus and Tran1} On review of literature, it is evident that children have more cardiorespiratory and less neurological and renal manifestations than adults. ^{Reference Fina, Dubus and Tran1−Reference Gendelman, Zeft and Spalding3} Cardiac involvement in eosinophilic granulomatosis polyangiitis leads to poor prognosis and mortality. Cardiac manifestations commonly include pericarditis, myocarditis, hypertension, arrhythmias, myocardial infarction, cardiomyopathy, and valvular regurgitation. ^{Reference Fina, Dubus and Tran1}

To our knowledge, this combination of myocarditis, cardioembolic stroke due to intracardiac thrombus, and endomyocardial fibrosis has not been previously reported. ^{Reference Fina, Dubus and Tran1−Reference Zwerina, Eger, Englbrecht, Manger and Schett4,Reference Amaddeo, Ventura and Marchetti6−Reference Albahri, Minxová, Lukeš, Mawiri and Štefáčková8} Albahri et al. described a 17-year-old girl with myocardial fibrosis and mitral regurgitation whose cardiac findings recovered on follow-up, unlike our patient where endomyocardial fibrosis and severe mitral regurgitation were persistent until death. ^{Reference Albahri, Minxová, Lukeš, Mawiri and Štefáčková8} Intracardiac thrombus is a rare manifestation in paediatric eosinophilic granulomatosis polyangiitis, to our knowledge, having been reported in only one case by Eleftheriou et al. ^{Reference Eleftheriou, Gale, Pilkington, Fenton, Sebire and Brogan2} Moreover, intracardiac thrombus, causing systolic obliteration of left ventricular mid-cavity, has not been previously reported in children. A similar case has been reported in an adult where there was systolic obliteration of left ventricular cavity with high pressure gradient. This was thought to be a high-risk factor for releasing thrombi into the systemic circulation. ^{Reference Ito, Fujita, Kanzaki, Sohmiya and Hoshiga9} Paediatric eosinophilic granulomatosis polyangiitis presenting with myocarditis is also rare. The prevalence of myocarditis was 22 and 40% according to two adult series. ^{Reference Moradinejad, Rezaei and Ziaee7}

We deferred histopathological confirmation because our patient satisfied four out of six criteria of American College of Rheumatology – asthma, eosinophilia >10%, non-fixed pulmonary infiltrates, and paranasal sinus abnormality. Also, biopsy would require invasive pulmonary or cardiac tissue in our patient. Histopathology is generally the gold standard for diagnosis. Histopathological findings include extravascular eosinophils, granulomas, and necrotising vasculitis. ^{Reference Fina, Dubus and Tran1} All these findings are not commonly seen in paediatric EGPA biopsy samples. Eosinophilic infiltrates are commoner when compared to vasculitis and granulomas. This is explained by the theory that children usually have a shorter period between the onset of allergic symptoms and systemic manifestations leading to earlier diagnosis during the eosinophilic phase when compared to adults who are usually diagnosed during the vasculitis phase. This explains the different presentations in children. ^{Reference Fina, Dubus and Tran1}

Our patient’s cardiac findings failed to improve inspite of early aggressive treatment. Pathological studies suggest that myocardial fibrosis can develop early and rapidly and lead to poor long-term prognosis in children ^{Reference Guillevin, Cohen, Gayraud, Lhote, Jarrousse and Casassus10} like in our case. Though she had an aggressive form of the disease with extensive cardiac involvement, she was in NYHA class I for almost 2 years after diagnosis. She unexpectedly developed a severe form of sepsis possibly contributed by immunosuppressive medication, a known complication.

Cardiac involvement can often be subclinical. Hence, it is our opinion that early detection by appropriate investigations including echocardiography and cardiac MR is mandatory in all suspect cases. This is paramount in children who often have cardiac involvement, higher chance of relapse, and mortality. If detected early before the myocardial fibrosis stage, aggressive treatment can significantly alter the course of the disease and hopefully lead to a better outcome.