Pediatric Myxedema Due to Autoimmune Hypothyroidism: A Rare Complication of a Common Disorder

In children, hypothyroidism usually presents non-specific symptoms; symptoms can emerge gradually, compromising a timely diagnosis. We report the case of a 13-year-old male, who was admitted to the hospital due to swelling of the torso and neck. Besides these symptoms, the child was healthy, except for a significant growth delay. Ultrasound evaluation and blood tests led to the diagnosis of myxedema secondary to severe hypothyroidism, which was due to autoimmune thyroiditis. Further investigations revealed pericardial effusion and pituitary hyperplasia, with hyper-prolactinemia. Treatment with levothyroxine led to edema regression and clinical, hemato-chemical and radiological improvement. After 6 months, growth velocity increased, although the recovery of growth already lost was not guaranteed. Brain MRI showed regression of pituitary hyperplasia. The diagnostic delay in this case was probably due to the patient's apparent good health, and the underestimation of growth restriction. This report underlines the importance of growth monitoring in adolescence, a critical period for identifying endocrine conditions; if undiagnosed, these conditions can lead to serious complications, such as myxedema in hypothyroidism, with potential effects beyond growth on multiple organs.