A common problem in an unusual setting

We present the case of a patient with an intrathoracic mass. Anthony Weetman, professor of medicine in Sheffield, comments on the case summary.

Case history

A 45 year old woman presented with a three month history of dyspnoea, itchy skin, palpitations, increased sweating, loose stools, orthopnoea, and muscle weakness. On examination she looked unwell, and she had a pulse of 200 beats/min in atrial fibrillation, a jugular vein pulse raised 5-6 cm, normal heart sounds, and a central trachea with bibasal crackles. The thyroid was not palpable. Electrocardiography confirmed atrial fibrillation. Echocardiography showed trivial mitral and tricuspid regurgitation with minimally impaired ventricular function.

A chest x ray film showed a mass adjacent to the left heart border; on lateral view it was located anteriorly with a well defined smooth superior border(fig 1). Computed tomography showed a left sided anterior mediastinal mass (fig 2). After injection of intravenous contrast medium, the heart and the great vessels were enhanced normally, with minimal enhancement of the mass 2 (centre)). Radiologically, the differential diagnosis (box) included an ectopic thyroid, but the characteristic features of continuity with the thyroid in the neck and intense enhancement with contrast were lacking( fig 2).