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Open access

Georgios Velimezis, Argyrios Ioannidis, Sotirios Apostolakis, Maria Chorti, Charalampos Avramidis and Evripidis Papachristou

Summary

During embryogenesis, the thymus and inferior parathyroid glands develop from the third pharyngeal pouch and migrate to their definite position. During this process, several anatomic variations may arise, with the thyroid being one of the most common sites of ectopic implantation for both organs. Here, we report the case of a young female patient, who underwent total thyroidectomy for papillary carcinoma of the thyroid. The patient’s history was remarkable for disorders of the genitourinary system. Histologic examination revealed the presence of well-differentiated intrathyroidal thymic tissue, containing an inferior parathyroid gland. While each individual entity has been well documented, this is one of the few reports in which concurrent presentation is reported. Given the fact that both the thymus and the inferior parathyroid are derivatives of the same embryonic structure (i.e. the third pharyngeal pouch), it is speculated that the present condition resulted from a failure in separation and migration during organogenesis.

Learning points:

  • Intrathyroidal thymus and parathyroid are commonly found individually, but rarely concurrently.

  • It is a benign and asymptomatic condition.

  • Differential diagnosis during routine workup with imaging modalities can be challenging.

Open access

Lauren J Baker, Anthony J Gill, Charles Chan, Betty P C Lin and Bronwyn A Crawford

Summary

In 2006, a 58-year-old woman presented with thyrotoxicosis. She had undergone left hemithyroidectomy 14 years before for a benign follicular adenoma. Ultrasound imaging demonstrated bilateral cervical lymphadenopathy with enhanced tracer uptake in the left lateral neck on a Technetium-99m uptake scan. Fine-needle aspiration biopsy of a left lateral neck node was insufficient for a cytological diagnosis; however, thyroglobulin (Tg) washings were strongly positive. The clinical suspicion was of functionally active metastatic thyroid cancer in cervical lymph nodes. A completion thyroidectomy and bilateral cervical lymph node dissection were performed. Histology demonstrated benign multinodularity in the right hemithyroid, with bilateral reactive lymphadenopathy and 24 benign hyperplastic thyroid nodules in the left lateral neck that were classified as parasitic thyroid nodules. As there had been a clinical suspicion of thyroid cancer, and the hyperplastic/parasitic thyroid tissue in the neck was extensive, the patient was given ablative radioactive iodine (3.7 GBq). After 2 years, a diagnostic radioactive iodine scan was clear and the serum Tg was undetectable. The patient has now been followed for 7 years with no evidence of recurrence. Archived tissue from a left lateral neck thyroid nodule has recently been analysed for BRAF V600E mutation, which was negative.

Learning points

  • Thyrotoxicosis due to functional thyroid tissue in the lateral neck is very rare and may be due to metastatic thyroid cancer or benign parasitic thyroid tissue.

  • Parasitic thyroid nodules should be considered as a differential diagnosis of lateral neck thyroid deposits, particularly where there is a history of prior thyroid surgery.

  • Parasitic thyroid nodules may occur as a result of traumatic rupture or implantation from a follicular adenoma at the time of surgery.

  • The use of ablative radioactive iodine may be appropriate, as resection of all parasitic thyroid tissue can prove difficult.

  • BRAF mutational analysis of parasitic thyroid tissue may provide extra reassurance in the exclusion of papillary thyroid carcinoma.

Open access

Mauro Boronat, Juan J Cabrera, Carmen Perera, Concepción Isla and Francisco J Nóvoa

Summary

A man underwent total thyroidectomy for goiter when he was 62 years old. The pathology report informed on a 5.5 cm oncocytic follicular adenoma and a 3.5 mm papillary microcarcinoma. Due to the papillary tumor, he was treated with ablative radioiodine therapy and suppressive doses of levothyroxine. After uneventful follow-up for 9 years, increased levels of serum thyroglobulin were detected. Further imaging studies including a whole body scan (WBS) after an empirical dose of 200 mCi 131I were negative. Two years later, a 99mTc SestaMIBI WBS and a 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography showed a well-delimited focal uptake in the right femur. A bone biopsy of the lesion demonstrated metastasis of follicular thyroid carcinoma. Retrospective histological reexamination of available material from the primary oncocytic thyroid tumor failed to reveal definitive traits of malignancy.

Learning points

  • Oncocytic follicular thyroid tumors are a relatively uncommon variant of follicular thyroid neoplasms mostly composed of distinctive large oxyphilic cells (Hürthle cells).

  • Criteria for the distinction between benign and malignant oncocytic neoplasms are not different from those used in the diagnosis of ordinary follicular tumors.

  • Some cases of apparently benign oncocytic neoplasms have been found to develop malignant behavior.

  • Search to rule out vascular and capsular invasion should be particularly exhaustive in histological assessment of oncocytic thyroid tumors.

  • Even so, long-term surveillance remains appropriate for patients with large apparently benign oncocytic tumors.