Intrathyroidal ectopic thymic tissue may mimic thyroid cancer: a case report

: Ectopic intrathyroidal thymus tissue that may be present as a thyroid nodule is rarely reported. We present a case of a 4-year-old boy with a solitary thyroid nodule. Real-time thyroid ultrasound showed a calcified nodule in the right lobe. Complete blood count, serum calcitonin, and thyroglobulin concentration were normal and antithyroid antibodies were negative. Fine-needle aspiration (FNA) biopsy was revealed as inadequate for cytological examination. During his follow-up, nodular enlargement was found, and the patient was subjected to surgical total excision of the right lobe of the thyroid gland. Pathological examination showed an ectopic intrathyroidal thymus tissue. In childhood, ectopic intrathyroidal thymus tissue can present as an enlarging microcalcified thyroid nodule that may mimic thyroid cancer and may grow during follow-up.