Introduction: We report 2 patients with Graves’ disease (GD) who had ‘silent’ thyroid cancers.
Case 1: A 20yo female was diagnosed with GD (clinical signs of Graves’ ophthalmopathy, goitre, sinus tachycardia, unintentional weight loss; TSH <0.005mIU/L [0.40-3.50mIU/L]; FT4 40.9pmol/L [9.0-19.0pmol/L]; FT3 >46.1pmol/L [2.6-6.0pmol/L]; TRAb 27.5IU/L [<1.0IU/L]). She commenced on carbimazole.
Her initial thyroid ultrasound (January 2017) demonstrated a heterogenous, hypervascular goitre, , which had on her repeat ultrasound (April 2017) increased in size. A thyroid technetium scan revealed diffuse radiotracer uptake (82.51%).
Due to refractory GD, a total thyroidectomy was performed (February 2018), revealing a 60mm papillary thyroid carcinoma in the right lobe and a 36mm papillary thyroid carcinoma in the left lobe, with lymphovascular and adipose tissue invasion. The tumours were negative for BRAF V600E.
Six weeks post-thyroidectomy, she had a thyroglobulin level at 16.3μg/L [0-28μg/L], undetectable anti-thyroglobulin antibody and TRAb 4.4IU/L. Radioactive iodine remnant ablation is planned.
Case 2: A 44yo female had severe thyrotoxicosis from GD (clinical signs of sinus tachycardia, unintentional weight loss, lid-lag and goitre; TSH <0.005mIU/L; FT4 43.1pmol/L; FT3 >46.1pmol/L; TRAb 176IU/L) requiring propanolol and carbimazole. A thyroid technetium scan revealed diffuse radiotracer uptake consistent with GD.
She was refractory to treatment, developing Grave’s ophthalmopathy. A total thyroidectomy was performed (July 2015). Histopathology revealed a 12mm follicular thyroid cancer in her left lobe, surrounded by Graves’ thyroiditis. Lymphovascular and right lobe invasion were not present. Radioactive iodine ablation was performed in Sept 2015, with a whole-body I-123 scan indicating absent residual iodine-avid tissue. She has not had recurrence of her follicular thyroid carcinoma.
Patients with GD have an increased risk of thyroid carcinomas, possibly related to TRAbs. It is usually either clinically apparent or occult micro-carcinomas. Large papillary thyroid carcinomas in GD not detected by thyroid scan or ultrasound is rare.