Intrathyroidal Ectopic Thymus Research Articles

Intrathyroidal Thymic Tissue Surrounding an Intrathyroidal Parathyroid Gland, the Cause of a Solitary Thyroid Nodule in a 6-Year-Old Boy

Ectopic intrathyroidal thymic tissue is a rare occurrence; parathyroid glands sometimes occur in an intrathyroidal location, but this is uncommon. We report a 6-year-old boy who was noted to have a solitary thyroid nodule on ultrasound. A hemithyroidectomy was performed, and histological investigation revealed that the nodule consisted of ectopic intrathyroidal thymus tissue surrounding a well-defined parathyroidal gland. This condition is an exceedingly rare cause of a thyroid nodule, but intrathyroidal thymic tissue should probably be included in the differential diagnosis of solitary thyroid nodules.

Ectopic intrathyroidal thymus misdiagnosed as a thyroid nodule: Sonographic appearance

An 11-year-old boy under suppression therapy for a solitary thyroid nodule was referred for sonographic examination. The diagnosis had been made at another institution, based only on sonography without cytopathologic verification. A small fusiform lesion, which was homogeneously hypoechoic with diffuse bright internal echoes, was demonstrated in the right lower pole of the thyroid. A normal elongated thymus with a cervical component was then found connected to the thyroid with an accessory lobe, which was embedded in the lower thyroid pole mimicking a solitary nodule. We discuss the developmental abnormalities of the thymus and their clinical significance in childhood with a brief review of the literature.

A Six-Year-Old Boy with a Suspicious Thyroid Nodule: Intrathyroidal Thymic Tissue

Ectopic intrathyroidal thymus tissue that forms mass lesions as a consequence of aberrant thymic migration during embryogenesis is rarely reported in the literature. We present the case of a 6-year-old boy with a right thyroid nodule and bilateral cervical lymph nodes. Thyroid hormone, antibodies, and routine chemistry tests were normal. Real-time thyroid ultrasound showed a right calcified nodule measuring 8 x 5 x 7 mm and multiple bilateral cervical lymph nodes. I131 scan showed mild decreased uptake in the right upper lobe. On fine-needle aspiration biopsy we discovered an atypical lymphoid proliferation that was suspicious, although not diagnostic, of a lymphoma. Immunostain for calcitonin was negative. Flow cytometry of the thyroid nodule aspirate demonstrated an abnormal polyclonal T cell population with dual expression of CD4 and CD8, and a subpopulation of cells that expressed TdT suggesting the possibility of lymphoblastic lymphoma. DNA analysis, as well as polymerase chain reaction for T cell and B cell gene rearrangement, did not demonstrate changes in the gene for the heavy chain of immunoglobulin of B cells and gamma chain of the T cell receptor. Lymph node aspirate showed unremarkable T and B lymphoid cells. The diagnosis of ectopic intrathyroidal thymus was made after the operation. Ectopic thymus tissue should be considered in the differential diagnosis of thyroid masses, especially in children.