A 3-year-old female presented with an anterior neck swelling of unspecified duration. She had no associated symptoms, and her thyroid function tests were within normal limits, with a thyroid-stimulating hormone (TSH) level of 0.98 and free thyroxine (FT4) of 18.
A 3-year-old female presented with an anterior neck swelling of unspecified duration. She had no associated symptoms, and her thyroid function tests were within normal limits, with a thyroid-stimulating hormone (TSH) level of 0.98 and free thyroxine (FT4) of 18.
A neck ultrasound revealed a single, well-defined, solid isoechoic nodule measuring 16x6x5 mm located in the mid to lower third of the left thyroid lobe. The nodule was classified as a TI-RADS 3 lesion, suggesting a low risk of malignancy.
Given the characteristics of the nodule and the patient’s young age, the case was discussed in a Multi-Disciplinary Team (MDT) meeting. A decision was made to proceed with a left thyroid lobectomy to obtain a definitive diagnosis and rule out malignancy. The surgery was performed without complications.
The histopathology report confirmed the presence of benign active intrathyroidal thymic tissue with no evidence of malignancy.
This case highlights a rare but benign condition, where intrathyroidal thymic tissue mimics a thyroid nodule in a pediatric patient. The diagnosis was confirmed postoperatively, and no further intervention was required.
