Autoimmune thyroid disease and allergic contact dermatitis: two immune-related pathologies in the same patient.

A 12-year-old girl presented signs and symptoms of hyperthyroidism. She had a firm goiter (II°) and she stated that she felt constant warmth, nervousness and experienced palpitations. Autoimmune hyperthyroidism was diagnosed (TSH 0.022 mIU/L↓; fT4 21.0 pmol/L; fT3 7.5 pmol/L↑; antithyroperoxidase antibodies 1148.0 U/mL↑; antithyroglobulin antibodies 41.4 U/mL; thyroid-stimulating hormone receptor antibodies 2.3 U/L↑). Thyroid ultrasound showed multiple hypoechogenic areas with increased vascular flow. During treatment with methimazole, a small hyperpigmented and moderately irritated region was found on the right side of the umbilicus. It was not an allergic skin reaction to methimazole but the classic contact allergic dermatitis, probably a result of nickel in her belt. Two years after stopping the treatment she returned to clinics. She was euthyroid but manifested a firm goiter and ultrasonographic features of autoimmune thyroid disease. The diagnostic work-up concerning antithyroid antibodies is mandatory to confirm the ongoing autoimmune process with a long-term significance.