Simultaneous occurrence of Graves' disease in eutopic and ectopic thyroid tissues: A case report and review of literature

Coexistence of Eutopic Thyroid Gland and Ectopic Thyroid Tissue: Rare but Not Uncommon

Ectopic thyroid tissue is very rare, but the coexistence of ectopic and eutopic thyroid glands is even more rare. The recognition of this diagnosis is important in patients who are being treated for thyrotoxicosis, but it is also crucial to exclude other associated serious disease conditions. In this article, we report three different cases that showed ectopic thyroid tissue with the coexisting presence of an eutopic thyroid gland. All three cases showed different outcomes. The recognition of this condition is of great importance because it alerts the referring physicians to this rare, yet possible occurrence and the potential pathological conditions associated with it. The first case showed how imaging could help outline even small ectopic thyroid tissue outside of the neck region even in cases where histopathological confirmation is difficult. The second case was very rare as thyroid carcinoma originated in ectopic thyroid tissue. In the last case, the initial imaging was misleading as it mimicked greatly ectopic thyroid tissue, and only detailed history and careful inspection of the images could lead to the correct interpretation of the findings.

Graves' Disease in Eutopic Thyroid with Ectopic Mediastinal Thyroid Tissue: Role of Single Photon Emission Computed Tomography-Computed Tomography

Ectopic thyroid is a rare embryological aberration due to defective migration. Most patients with ectopic thyroid tissue have absent thyroid gland in normal anatomical position and present with hypothyroidism. We present a patient with Graves' disease in the eutopic thyroid with ectopic thyroid tissue in the mediastinum and usefulness of single-photon emission computed tomography-computed tomography.

Simultaneous Occurrence of Thyroiditis in Ectopic and Eutopic Thyroid Masquerading as Thyroglossal Cyst

Ectopic thyroid gland is a rare condition usually presenting with neck swelling or hypothyroidism. In most cases, ectopic thyroid tissue is the only functioning thyroid tissue, but it may rarely be associated with normal thyroid gland. Thyroiditis in an ectopic thyroid gland is very rare. Here, we describe a 13-year-old girl who was initially suspected, as a having a thyroglossal cyst. Thyroid functions were suggestive of thyrotoxicosis. She was diagnosed to have simultaneous occurrence of thyroiditis in the ectopic and eutopic thyroid glands. This case was exceedingly rare since this patient presented with thyrotoxicosis unlike previous reported cases who were either euthyroid or hypothyroid.

Graves' disease in a mediastinal mass presenting after total thyroidectomy for nontoxic multinodular goiter: a case report

BACKGROUND

Thyrotoxicosis after total thyroidectomy is mostly iatrogenic. Rarely, a hyperfunctional thyroid remnant or ectopic tissue may be the cause. There are few cases of Graves' disease arising from thyroid tissue located in the mediastinum and none in which Graves' disease was diagnosed only after surgery. We report the case of a patient with Graves's disease in a mediastinal thyroid mass presenting 7 years after total thyroidectomy for nontoxic goiter.

CASE PRESENTATION

A 67-year-old Caucasian woman presented with palpitations, fatigue and weight loss. She had a history of total thyroidectomy for nontoxic multinodular goiter at the age of 60 without any signs of malignancy on microscopic examination. She had been medicated with levothyroxine 100 μg/day since the surgery without follow-up. She was tachycardic, had no cervical mass or eye involvement. Her thyroid-stimulating hormone levels were suppressed (0.000 μU/mL) and her free thyroxine (3.22 ng/dL) and free triiodothyronine (8.46 pg/mL) levels increased. Neither mediastinal enlargement nor trachea deviation was found on chest roentgenogram. Levothyroxine treatment was stopped but our patient showed no improvement on free thyroxine or free triiodothyronine 10 days later. Thyroglobulin was increased to 294 mg/mL. A cervical ultrasound scan revealed no thyroid remnant. Her anti-thyroid-stimulating hormone receptor antibodies were high (19.7 U/L). Corporal scintigraphy demonstrated increased intrathoracic radioiodine uptake. A computed tomography scan confirmed a 60 × 40 mm mediastinal mass. Methimazole 10 mg/day was started. Three months later, her thyroid function was normal and she underwent surgical resection. Microscopic examination showed thyroid tissue with no signs of malignancy.

CONCLUSIONS

Although thyrotoxicosis after total thyroidectomy is mostly due to excessive supplementation, true hyperthyroidism may rarely be the cause, which should be kept in mind. The presence of thyroid tissue after total thyroidectomy in our patient may correspond to a remnant or ectopic thyroid tissue that became hyperfunctional in the presence of anti- thyroid-stimulating hormone receptor antibodies.