Unmasking of childhood hypothyroidism by disseminated xanthomas.

Secondary hyperlipidemia is a common laboratory finding in children with nephrotic syndrome, diabetes mellitus, and hypothyroidism. However, clinical signs of hyperlipidemia are extremely rare in childhood. We report on an 11-year-old girl who presented with a disseminated yellow papulomatous rash on the lower limbs and yellow skin creases on the palms of her hands. Blood tests yielded an opaque serum with a triglyceride concentration of 820 mg/dL and cholesterol of 1050 mg/dL. Skin biopsy of one of the papules confirmed the diagnosis of xanthomas. Additional examinations revealed clinical (weight gain, diminished growth rate) and biochemical primary hypothyroidism (free T4: 0.4 ng/L [normal 8-22 ng/L]; thyroid-stimulating hormone: >200 mU/L) as a consequence of Hashimoto thyroiditis (thyroid peroxidase and thyroglobulin: 4400 U/mL and >2000 U/mL, respectively; normal <60 U/mL). The patient was started on L-thyroxine, which led to a gradual decline of cholesterol and triglycerides to normal concentrations and a complete remission from the xanthomatous rash. For the first time, this case depicts disseminated xanthomas of the skin as the presenting complaint of severe hypothyroidism. hyperlipidemia, hypothyroidism, xanthoma.