Solitary thyroid nodule as presenting symptom of Pendred syndrome caused by a novel splice-site mutation in intron 8 of the SLC26A4 gene.

UNLABELLED: Thyroid nodules are a rare occurrence in children but represent an important clinical problem because of the possibility of malignancy. We report the case of a 4-year-old boy with sensorineural deafness, who presented with a painless mass in the right anterior cervical region. Cervical ultrasound demonstrated a solid nodule (1.4 x 2.5 x 1.7 cm) in the right thyroid lobe. Thyroid function tests revealed compensated hypothyroidism (free T4 1.0 ng/dl; TSH 57 mIU/l) with no detectable thyroid antibodies. A 99mTc thyroid scan showed a generalised slightly increased tracer retention (4.6%) with an enlarged right lobe, without distinct nodules. A fine-needle aspiration biopsy revealed normal follicular cells. The boy was treated with l-thyroxine which resulted in a complete clinical and sonographical disappearance of the nodule. A CT scan of temporal bones revealed a bilaterally enlarged vestibular aqueduct with Mondini malformation of the cochlea. The combination of all these symptoms suggested the diagnosis of Pendred syndrome (PDS), a disorder characterised by congenital sensorineural hearing loss and a variable degree of thyromegaly due to mutations in the SLC26A4/PDSgene. DNA analysis disclosed a so far unreported homozygous splice site mutation (1002-4 C>G) in intron 8 of the SLC26A4 gene confirming this diagnosis.
CONCLUSION: a solitary thyroid nodule may therefore be another presenting symptom of thyroid involvement in Pendred syndrome