Endocrine Abstracts

Introduction: Ectopic benign thyroid tissue outside the normal migration path of the thyroid is an extremely rare condition that, to our knowledge, has never been described in the orbit.

Clinical case: 75-year-old woman with nodular thyroid was referred to Vilnius University Hospital Santariskiu Klinikos for fine needle aspiration biopsy. Her complaints were palpitations, difficulty swallowing, diplopia, exophthalmos with medial and –superior dislocation. Symptoms were progressing for 2 years, although laboratory testing always showed euthyreosis. Her thyroid-stimulating hormone (TSH) was 1.04 mU/l (normal 0.4–4.1 mU/l), anti-TPO antibodies – 1.9 kU/l (<5.61 kU/l) on admission. Fine needle aspiration biopsy and histological examination suggested diagnosis of Hurthle cell carcinoma and subject was referred to surgery.

Management and Outcome: After thyroidectomy histology revealed nodular thyroid hyperplasia and follicular adenoma. To exlude orbital malignancy head MRI was performed. Imaging showed 18×14 mm in size, non-homogenic, contrast accumulating mass with well-defined margins in the inferior –lateral part of the orbit. Orbital tumor excision was performed and histological examination revealed tumor composed of micro-/macrofolicules with colloid. Folicular epithelium had no atypical changes, as confirmed by three independed pathologists. These criteria supported diagnosis of ectopic thyroid tissue. Due to patients noncompliance further postoperative period is unknown. A 5-year follow-up showed normal TSH levels of 3.07 mU/l, with 75 mcg/day levothyroxin therapy, anti-TPO antibodies – 0.2 kU/l, thyroglobulin 0.91 mgk/l (normal 0.83–55 mgk/l). Once no primary or secondary tumors were detected we concluded that the thyroid tissue in the orbit of our patient was ectopic.

Conclusion: Ussualy ectopic benign thyroid tissue could be found in the normal migration path of the thyroid. However, we are presenting the extremely rare case of benign thyroid tissue located in the orbit, suggesting the extensive diagnostic approach in unclear cases.