Iris ectopic thyroid tissue: report of a case

Ectopic thyroid tissue in the iris: a case report

BACKGROUND

Ectopic thyroid tissue in the iris, also known as a thyroid glandular epithelial choristoma of the iris, has only been described twice in the literature. In both cases it remained asymptomatic.

CASE PRESENTATION

A 67-year-old female patient presented for the first time in mid-2017 with corneal endothelial decompensation, with a history of complicated cataract surgery and IStent® implantation. Slit lamp microscopy showed endothelial decompensation, pseudophakia, anterior synechiae and a whitish iris tumour adhering to the endothelium. The latter had existed since childhood. Given these findings, reduced visual acuity of hand movement perception and an intraocular pressure of 23 mmHg, we performed a keratoplasty combined with an en bloc resection of the iris tumour at 9 o'clock and sector iridectomy at the end of 2019. Histological and immunohistological examination of the iris tumour unexpectedly revealed thyroid tissue. After the procedure described above, the patient had an increase in visual acuity while the graft stayed clear and the eye showed no evidence of tumour recurrence or other complications.

CONCLUSIONS

We report a third case of ectopic thyroid tissue in the iris. Both previous cases remained asymptomatic, whereas in our case, size and location of the ectopic thyroid tissue contributed to a more complex cataract surgery resulting in endothelial decompensation. Therefore, in such cases appropriate patient information should be provided prior to cataract surgery. Furthermore, careful histological examination and examination of the thyroid is important to exclude malignant diagnoses such as a metastasis of a follicular thyroid carcinoma.

Prevalence, diagnosis and management of ectopic thyroid glands

Ectopic thyroid tissue (ETT) is an uncommon entity that may be found anywhere along the line of the obliterated thyroglossal duct, usually from the tongue to the diaphragm. We performed a retrospective analysis of patients undergoing surgical treatment for thyroid disease between January 2000 and December 2013, seeking for ETT All patients with prior neck surgery or trauma were excluded. The clinic-pathologic features, prevalence and diagnosis of the lesions were collected and analyzed. Out of 3092 included patients, 28 ETT were identified (0.9%). The anatomical site of ETT was as follows: lateral cervical in 6 (21.4%), along the thyroglossal duct in 6 (21.4%), mediastinal in 5 (17.9%), lingual in 5 (17.9%), sublingual in 3 (10.7%), and submandibular in 3 (10.7%). Histopathology revealed 27 benign lesions and 1 (3.6%) papillary carcinoma. ETT is found in less than 1% of patients receiving thyroid surgery. Diagnosis of ETT requires clinical imaging. Surgery is a prudent choice due to the potential of malignant evolution of ETT.

Ectopic thyroid tissue in the adrenal gland: report of a case

Foci of ectopic thyroid tissue are uncommon. Most sites of thyroid ectopia are confined to the neck region. The presence of ectopic thyroid tissue outside the migration pathway of the primitive thyroid in other locations is exceptional. Given that any disease of the thyroid gland may also affect ectopic thyroid tissue, pathologists has to recognize benign or malignant conditions that may develop in the ectopic focus. We present the case of a 32-year-old woman with ectopic thyroid parenchyma in the adrenal gland. Clinically, postoperative thyroid ultrasound echography and computed tomography scans did not reveal any thyroid tumor. The ectopic tissue was a cyst bordered by mature follicular thyroid structures and was histologically benign, without the molecular alterations associated with malignant tumors of follicular cell derivation (BRAFV600E, N-RAS, H-RAS, K-RAS). Review of the literature reveals that adrenal ectopic thyroid tissue is nearly always cystic and has distinctive pathologic features.

Morphological, diagnostic and surgical features of ectopic thyroid gland: a review of literature

Ectopic thyroid tissue remains a rare developmental abnormality involving defective or aberrant embryogenesis of the thyroid gland during its passage from the floor of the primitive foregut to its usual final position in pre-tracheal region of the neck. Its specific prevalence accounts about 1 case per 100.000-300.000 persons and one in 4.000-8.000 patients with thyroid disease show this condition. The cause of this defect is not fully known. Despite genetic factors have been associated with thyroid gland morphogenesis and differentiation, just recently some mutation has been associated with human thyroid ectopy. Lingual region in the most common site of thyroid ectopy but ectopic thyroid tissue were found in other head and neck locations. Nevertheless, aberrant ectopic thyroid tissue has been found in other places distant from the neck region. Ectopic tissue is affected by different pathological changes that occur in the normal eutopic thyroid. Patients may present insidiously or as an emergency. Diagnostic management of thyroid ectopy is performed by radionuclide thyroid imaging, ultrasonography, CT scan, MRI, biopsy and thyroid function tests. Asymptomatic euthyroid patients with ectopic thyroid do not usually require therapy but are kept under observation. For those with symptoms, treatment depends on size of the gland, nature of symptoms, thyroid function status and histological findings. Surgical excision is often required as treatment for this condition.

Ectopic mediastinal goiter successfully managed via cervical approach: case report and review of the literature

BACKGROUND

Ectopic mediastinal goiter is a rare entity that presents diagnostic and treatment challenges to the clinician.

METHODS

A case of primary ectopic mediastinal goiter is presented and use of a cervical approach for excision is described herein. Additionally, precedent literature highlighting surgical treatment approaches is reviewed.

RESULTS

The distinction between primary and secondary ectopic mediastinal goiter is significant as this indicates the vascular supply to the ectopic mass. Previous authors suggested open thoracic procedures for all primary mediastinal goiters to safely divide intrathoracic vascular supply, but favorably positioned anterior mediastinal goiter may be safely removed via cervical approach. This is the second case of primary ectopic mediastinal goiter successfully resected via cervical approach.

CONCLUSION

Select cases of primary mediastinal goiter may be amenable to excision via cervical approach, avoiding potential complications of open thoracic procedures. Additionally, CT-guided biopsy is an effective tool in preoperative diagnosis of anterior mediastinal masses.

Increased serum thyroglobulin levels and negative imaging in thyroid cancer patients: are there sources of benign secretion? A speculative short review

After thyroidectomy and 131I ablation for differentiated thyroid cancer (DTC), serum thyroglobulin (Tg) became a sensitive marker of residual disease. It is not uncommon to find patients at follow-up with persistent serum Tg levels and no other clinical or imaging evidence for the disease. The vast majority of these patients, most probably, have occult foci of disease, often in minute cervical lymph nodes. A review of the literature including papers published on PubMed/Medline until June 2010 was made. In this study we speculated that a minority of patients who had undergone surgery for differentiated thyroid cancer might have benign sources of Tg secretion at follow-up. These sources may be foci of radio-resistant ectopic thyroid tissue or a thyroid stimulating hormone-stimulated thymus.

Ectopic thyroid tissue within the gall bladder: case report and brief review of the literature

In this brief report, we describe a case of ectopic thyroid tissue in the gallbladder wall. We review the literature on ectopia of the thyroid and its rare occurrence outside the usual path of the migration of the thyroid anlage from the foramen caecum to the mediastinum. The importance of distinguishing ectopic thyroid from metastatic thyroid carcinoma is emphasized.

Ectopic submandibular thyroid tissue with a coexisting normally located multinodular goitre: case report and review of the literature

The simultaneous finding of submandibular ectopic thyroid tissue and functional orthotopic thyroid gland is an extremely rare event. The present report describes the case of a woman presenting with a left submandibular mass, distant from a palpable multinodular goitre. Ultrasonography showed an ovoidal solid mass adjacent to the lower margin of the left submandibular gland. Cytological specimens showed colloid material and thyroid follicular cells with no malignant features. A preoperative CT scan demonstrated a very thin connection between the thyroid and the submandibular mass. The patient underwent total thyroidectomy and excision of the submandibular mass. The histopathological diagnosis of the thyroid tissue was multinodular goitre, and the submandibular mass was ectopic thyroid tissue showing a hyperplastic pattern. The main differential diagnosis of the submandibular mass was a metastasis from a well differentiated cancer. This case illustrates that an ectopic thyroid off the midline may not necessarily be a metastasis from a thyroid cancer.

Selective pathologies of the head and neck in children: a developmental perspective

The range of pathology seen in the head and neck region is truly amazing and to a large extent probably mirrors the complex signaling pathways and careful orchestration of events that occurs between the primordial germ layers during the development of this region. As is true in general for the entire discipline of pediatric pathology, the head and neck pathology within this age group is as diverse and different as its adult counterpart. Cases that come across the pediatric head and neck surgical pathology bench are more heavily weighted toward developmental and congenital lesions such as branchial cleft anomalies, thyroglossal duct cysts, ectopias, heterotopias, choristomas, and primitive tumors. Many congenital "benign" lesions can cause significant morbidity and even mortality if they compress the airway or other vital structures. Exciting investigations into the molecular embryology of craniofacial development have begun to shed light on the pathogenesis of craniofacial developmental lesions and syndromes. Much more investigation is needed, however, to intertwine aberrations in the molecular ontogeny and development of the head and neck regions to the represented pathology. This review will integrate traditional morphologic embryology with some of the recent advances in the molecular pathways of head and neck development followed by a discussion of a variety of developmental lesions finishing with tumors presumed to be derived from pluripotent/progenitor cells and tumors that show anomalous or aborted development.