Thyroid Storm: A Rare Paraneoplastic Syndrome in an Infant With Hepatoblastoma

Abstract

Abstract Background: Graves disease (GD) is the most common cause of pediatric hyperthyroidism. Thyroid storm (TS) is a rare initial manifestation of GD and is typically triggered by an underlying stressor such as infection, trauma or surgery in a patient with underlying GD and poorly controlled hyperthyroidism. Clinical Case: A previously healthy 21-month-old Hispanic male presented to our ER due to concerns of acute abdominal pain. He was noted to have diffuse abdominal tenderness, unremitting anxiety and mild exophthalmos. Vital signs revealed tachycardia and hypertension. Initial lab evaluation was suggestive of primary hyperthyroidism (TSH<0.02 mcU/mL, n 0.5-4.5 mcU/mL, and free T4 at 5.8 ng/dL, n 0.8-2 ng/dL). His Burch-Wartofsky point scale score was 45, indicating high likelihood of TS. He was aggressively treated with methimazole, potassium iodide and propranolol. Five days later, there was a significant improvement in symptoms and labs (TSH<0.02 mcU/mL, n 0.5-4.5 mcU/mL, and free T4 2.3 ng/dL, n 0.8-2 ng/dL) and he was discharged home on methimazole and propranolol. Interestingly, all thyroid autoantibodies were negative including TSI, TRAb, anti-thyroglobulin and anti-TPO antibodies. His thyroid function continued to improve and propranolol was discontinued. Three weeks after his initial hospital admission, he developed a diffuse urticarial rash and the methimazole was held and propranolol restarted. Within a few days, he developed persistent fevers for which he was readmitted. His total T4 at that time was elevated at 23 mcg/dL (n 4.5-11 mcg/dL) and because the rash was improving, methimazole was restarted. In the following weeks, the patient continued to have intermittent fevers, diffuse waxing and waning rash, decreased activity, and reduced appetite. He was seen by his pediatrician who noted hepatomegaly. Abdominal CT and ultrasound revealed a liver mass (11 x 10 x 10 cm) and a 7 mm peripherally placed pulmonary nodule in the left lower lobe. The patient was admitted to the hematology/oncology unit for further evaluation. He was found to have an elevated alpha-fetoprotein level (AFP) of 43,051 ng/mL, n<6 ng/mL, which was concerning for hepatoblastoma (HB) that was confirmed by tissue biopsy. He was subsequently initiated on neoadjuvant chemotherapy. Methimazole dose requirements gradually decreased with eventual discontinuation 1 week after initiation of chemotherapy. He has remained clinically euthyroid off methimazole for almost 3 months with normal thyroid function. Conclusion: We report an unusual case of transient hyperthyroidism that initially presented as TS in a 21 month old male who was subsequently diagnosed with HB. Paraneoplastic syndromes (PNS) may occur with any tumor. Hyperthyroidism is occasionally associated with non-seminomatous germ-cell tumors with elevated HCG. We believe this is the first report of pediatric thyroid storm as a PNS in HB.