Incidental diagnosis of cardiac fibroma in an infant with acute viral bronchiolitis.

Objective: Pediatric cardiac tumors are rare and, among them, 90% are benign. Cardiac fibroma is the second most frequent tumor, after rhabdomyoma. The objective of this study is to report a case of cardiac fibroma diagnosed incidentally in a patient admitted with acute viral bronchiolitis.

Case description: A 5-month-old male infant was admitted to the pediatric emergency department with acute viral bronchiolitis requiring hospitalization. He presented a detectable respiratory syncytial virus in oropharyngeal swab, blood test with lymphocytosis and a chest radiography revealed cardiomegaly. Further cardiologic testing was performed detecting elevation of cardiac biomarkers, an electrocardiogram with alteration of left ventricular repolarization and echocardiogram with a heterogeneous mass in the left ventricular, with areas of calcification. A chest angiotomography suggested rhabdomyosarcoma or cardiac fibroma and a magnetic resonance showed a mass, with characteristics suggesting fibroma. The final diagnosis was made after two cardiac catheterizations for biopsy of the lesion, confirming cardiac fibroma by anatomopathological examination. Because the patient had moderate to severe systolic dysfunction, he was submitted to heart transplant.

Comments: One third of cardiac fibromas are asymptomatic, generally diagnosed late through tests ordered for other reasons. The gold-standard test for definitive diagnosis is biopsy. Cardiac fibroma usually does not present spontaneous regression and, in most cases, partial or total surgical resection is necessary. When tumors are unresectable, heart transplantation should be indicated. It is essential to have detailed characterization of the cardiac mass to establish the most appropriate therapeutic approach for each patient.