Introduction: Although uncommon, unilateral Graves’ disease (GD) can occur in a bilobar thyroid gland. We report an unusual case of not only unilateral GD, but also a concurrent aggressive form (tall cell variant) of papillary thyroid carcinoma (PTC).
Case: A 54yo male was referred with dysphonia, nervousness, unintentional weight loss of 7kg and diarrhoea for the last 3 months. He was cachexic and had a fine tremor. He had 2 non-tender nodules in his left thyroid gland.
He had suppressed TSH (<0.04mIU/L [0.20-3.5mIU/L]), elevated FT4 (51.7pmol/L [10.0-22.0pmol/L]) and FT3 levels (22.2pmol/L [3.2-6.3pmol/L]). Thyroid auto-antibodies (TRAb not measured) were normal and thyroglobulin level was 7IU/mL [0-60IU/mL]. Thyroid ultrasound identified an irregular, highly vascular, isoechoic nodule involving the superior and mid poles of the left lobe only [16x10x18mm]. His thyroid technetium scan demonstrated diffuse, avid radiotracer uptake, particularly in the superior and mid poles of the left lobe, whilst the right lobe remained suppressed. At the time, these investigations were reported as being consistent with toxic adenomata. He was commenced on carbimazole.
On the assumption that he had toxic adenomata of the left lobe, a left hemithyroidectomy was performed. Histopathology revealed an 11mm multifocal PTC, with features of a tall cell variant, in the left lobe. There were also diffuse, mild hyperplastic changes, consistent with treated GD. He had completion thyroidectomy 14 days later. Histopathology demonstrated a microscopic (0.5cm) PTC in the inferior pole of the right lobe.
Post-operatively he received radioiodine remnant ablation. He remains euthyroid, with no further recurrence of his PTC 12 years after initial presentation.
GD can occur unilaterally and imaging of the thyroid may be misleading. The exact aetiology for unilateral GD is unknown. Aggressive variants of PTC, such as the tall cell variant, are more frequent in patients with GD.