A teenager with recurrent supraventricular tachycardia and a giant mediastinal mass

Abstract

We describe a unique case of a teenager with past medical history of anxiety, dysmenorrhea and one year of recurrent symptomatic palpitations who was found to have an exceptionally large mediastinal teratoma which was compressing the right atrium, after evaluation for recurrent symptomatic supraventricular tachycardia. Our case adds new perspectives on the evaluation of what may seem to be an indolent arrhythmia. Her symptoms were initially thought to be secondary to her treatment with fluoxetine and oral combined contraceptives, which were discontinued but her symptoms persisted. A follow-up 12-lead electrocardiogram revealed normal sinus rhythm for which a 48-h Holter monitor was placed and yielded multiple episodes of overt AV node reentrant supraventricular tachycardia (SVT). She was referred to our center for evaluation for ablation for which she underwent routine pre-ablation echocardiography and was found to have an exceptionally large mediastinal mass consistent with a cystic teratoma significantly compressing the right atrium causing partial obstruction of the tricuspid annulus. The mass was successfully excised, and the pathology report revealed a 16cm cystic teratoma arising from thymic tissue. The mediastinum is the second commonest site to find a teratoma. These are congenital masses thought to arise from a defect in embryonal cell migration and by definition include all three embryonal cell layers, thus potentially may differentiate any kind of tissue. We emphasize the importance of pre-ablation imaging studies to evaluate for secondary causes of SVT, as catheter manipulation of the endocardium could have resulted in devastating consequences such as atrial rupture.

Keywords

• Teratoma
• Supraventricular Tachycardia
• Pediatric surgery