Pediatric toxic polycystic thyroid.

BACKGROUND: Polycystic thyroid disease (PCTD) is a rare condition and has been described in adults in the setting of subclinical and clinical hypothyroidism. We present the first known case of a pediatric patient with diffuse macrocystic degeneration of the thyroid.

CLINICAL PRESENTATION: A 6-year-old previously healthy patient was evaluated after presenting with a 16-month history of an enlarging polycystic thyroid and hyperthyroidism. Markers of autoimmune thyroid disease including thyroid stimulating immunoglobulin (TSI), thyroid stimulating hormone (TSH) receptor antibody, thyroid peroxidase antibody and thyroglobulin antibody were negative. No family history of benign or malignant thyroid or cystic disease was present. The patient underwent a total thyroidectomy without perioperative complication. She remains euthyroid with thyroid hormone replacement therapy.

SUMMARY: To our knowledge, this is the first report of PCTD in the pediatric population associated with hyperthyroidism without evidence of autoimmune disease. Somatic activating thyrotropin-receptor gene mutations are known to cause non-autoimmune hyperthyroidism in children, however it is unknown if similar mechanisms are responsible for pediatric PCTD.

CONCLUSIONS: Polycystic thyroid degeneration can occur in children and may result in a hyperthyroid state.