Delayed Diagnosis of Painless Thyroiditis in an Adolescent Presenting with Aggression and Disruptive Behavior Initially Attributed to Worsening of a Psychiatric Disorder.

Painless thyroiditis, which is rare in children, exhibits the characteristic sequence of hyperthyroidism, including aggressive and disruptive behaviors. Unlike subacute thyroiditis or Graves' disease, painless thyroiditis is challenging to diagnose because of its mild symptoms and minimal or absent physical findings. Moreover, aggressive and disruptive behaviors in children with psychiatric disorders may be misconstrued as exacerbation of underlying symptoms.