Ectopic poorly differentiated (insular) carcinoma of the thyroid. Report of a case presenting as an anterior mediastinal mass

Personalized Management of Malignant and Non-Malignant Ectopic Mediastinal Thyroid: A Proposed 10-Item Algorithm Approach

We aimed to analyze the management of the ectopic mediastinal thyroid (EMT) with respect to EMT-related cancer and non-malignant findings related to the pathological report, clinical presentation, imaging traits, endocrine profile, connective tissue to the cervical (eutopic) thyroid gland, biopsy or fine needle aspiration (FNA) results, surgical techniques and post-operatory outcome. This was a comprehensive review based on revising any type of freely PubMed-accessible English, full-length original papers including the keywords "ectopic thyroid" and "mediastinum" from inception until March 2024. We included 89 original articles that specified EMTs data. We classified them into four main groups: (I) studies/case series (n = 10; N = 36 EMT patients); (II) malignant EMTs (N = 22 subjects; except for one newborn with immature teratoma in the EMT, only adults were reported; mean age of 62.94 years; ranges: 34 to 90 years; female to male ratio of 0.9). Histological analysis in adults showed the following: papillary (N = 11/21); follicular variant of the papillary type (N = 2/21); Hürthle cell thyroid follicular malignancy (N = 1/21); poorly differentiated (N = 1/21); anaplastic (N = 2/21); medullary (N = 1/21); lymphoma (N = 2/21); and MALT (mucosa-associated lymphoid tissue) (N = 1/21); (III) benign EMTs with no thyroid anomalies (N = 37 subjects; mean age of 56.32 years; ranges: 30 to 80 years; female to male ratio of 1.8); (IV) benign EMTs with thyroid anomalies (N = 23; female to male ratio of 5.6; average age of 52.1 years). This panel involved clinical/subclinical hypothyroidism (iatrogenic, congenital, thyroiditis-induced, and transitory type upon EMT removal); thyrotoxicosis (including autonomous activity in EMTs that suppressed eutopic gland); autoimmune thyroiditis/Graves's disease; nodules/multinodular goiter and cancer in eutopic thyroid or prior thyroidectomy (before EMT detection). We propose a 10-item algorithm that might help navigate through the EMT domain. To conclude, across this focused-sample analysis (to our knowledge, the largest of its kind) of EMTs, the EMT clinical index of suspicion remains low; a higher rate of cancer is reported than prior data (18.8%), incident imagery-based detection was found in 10-14% of the EMTs; surgery offered an overall good outcome. A wide range of imagery, biopsy/FNA and surgical procedures is part of an otherwise complex personalized management.

[Ectopic tissue of the thyroid gland and the parathyroid glands]

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.

Ectopic Thyroid Tissue in the Mediastinum Characterized by Histology and Functional Imaging with I-123 SPECT/CT

Ectopic thyroid tissue is a rare entity and when discovered it is typically along the pathway of embryologic migration of the thyroid. We present a case of incidental finding of ectopic thyroid tissue within mediastinum in a 61-year-old female patient with a history of total thyroidectomy for thyroiditis and nodules. The patient presented to emergency room with cough and right chest pain and underwent a chest computed tomographic angiogram (CTA) to exclude pulmonary embolism as part of chest pain workup. One right paratracheal mediastinal soft tissue nodule was visualized on the images of CTA. This right paratracheal soft tissue mass was found to be ectopic benign thyroid tissue by histological analysis of the biopsied tissue samples. The function of this ectopic thyroid tissue was characterized by I-123 radioiodine uptake and single photon emission computed tomography/computed tomography (SPECT/CT) imaging. This case illustrates that ectopic thyroid tissue should be included for differential diagnosis of a hyperdense soft tissue mass located within mediastinum. I-123 SPECT/CT is useful for guiding tissue biopsy of ectopic thyroid tissue distant from orthotopic thyroid gland and functional and anatomic characterization of mediastinal ectopic thyroid tissue for surgical resection when it is medically necessary.

Insular variant of poorly differentiated thyroid carcinoma

OBJECTIVE

To present a case of an insular variant of poorly differentiated thyroid carcinoma (PDTC) and to review the literature related to diagnosis, natural history, and treatment of this unusual form of thyroid cancer.

METHODS

We present the clinical, laboratory, and pathologic findings of the study patient and review English-language literature related to PDTC published between 1970 and the present.

RESULTS

PDTC is a controversial and rare epithelial thyroid cancer, intermediate between differentiated thyroid carcinoma and anaplastic thyroid carcinoma that exhibits increased aggressiveness, propensity to local recurrence, distant metastases, and increased mortality. PDTC warrants aggressive management with total thyroidectomy followed by radioactive iodine ablation and potentially additional therapy for residual or recurrent disease. Some carcinomas do not take up radioactive iodine, and dedifferentiated clones of distant metastases may evolve. It is unclear whether chemotherapy is beneficial. Use of additional imaging modalities, including positron emission tomography, 18-fludeoxyglucose positron emission tomography/computed tomography, 18-fludeoxyglucose positron emission tomography/computed tomography/magnetic resonance imaging, (124)I positron emission tomography/computed tomography, positron emission tomography/magnetic resonance imaging fusion studies, and recombinant human thyrotropin-stimulated radioactive iodine uptake for cancer surveillance are discussed.

CONCLUSIONS

PDTC is an unusual and aggressive form of thyroid cancer. Fine-needle aspiration cytology may not yield sufficient information to specifically diagnose PDTC. Aggressive management with total thyroidectomy and neck dissection followed by high-dose radioactive iodine remnant ablation is standard. Iodine I 131 whole body scanning is often the initial test for tumor surveillance, with other imaging modalities applied as needed.

A review of thyroid cancer with intermediate differentiation

BACKGROUND AND OBJECTIVES

Tall cell (TCV), columnar cell (CCV), insular (IC), diffuse sclerosing (DSPTC) and solid/trabecular are uncommon subtypes of thyroid cancer, which have generally been described in case reports or small series in the world literature. Due to the rarity of these thyroid cancers, their clinical behavior remains incompletely understood. The aim of this review was to pool the currently available clinical information regarding these uncommon thyroid cancers so as to gain a better understanding of their clinical aspects and natural history.

METHODS

A computer-aided search of MEDLINE (1966-2001, PUBMED website) and CINAHL (1982-2001) databases was performed, as well as a review of the reference section of each primary study was done. All cases of TCV, CCV, DSPTC, solid/trabecular, and IC described in the English medical literature were identified. For the subtypes DSPTC, TCV, and IC, clinical data from the published case series were combined in a weighted analysis. Weighting was based on the number of cases per series. For the CCV and the solid/trabecular variant, due to the small number of cases, raw figures for the clinical features were obtained.

RESULTS

DSPTC (n = 65) appeared to have a tendency for intra-thyroidal extension (40%) and a high propensity for nodal metastates (68%). The mean overall tumor related mortality was similar to well differentiated thyroid cancer (WDTC) at only 2% at 8 years follow-up. The solid/trabecular variant was seen in 37% of the radiation induced thyroid tumors of the Chernobyl accident. It had a high propensity for extrathyroidal extension, and cervical lymph node metastases were found in up to 83% of patients. Unlike WDTC, TCV (n = 209) was a more aggressive tumor, associated with distant metastases in 22% of cases and had a mean tumor related mortality of 16%. The histological diagnosis of TCV was a poor prognostic factor regardless of patient age or tumor size. The CCV (n = 41) had a high overall mortality rate of 32%. When encapsulated, however, CCV had an excellent prognosis similar to that found in WDTC. In contrast, CCV tumors that were not encapsulated had extrathyroidal spread in 67% and had distant metastases in 87% of patients. The variant of IC (n = 213) appeared to be an aggressive subtype of thyroid cancer. The mean loco-regional recurrence and/or distant metastases rate was 64% and tumor related mortality was high at 32%.

CONCLUSIONS

DSPTC, TCV, CCV, and IC are thyroid cancer subtypes, which have a biological aggressiveness, which appear to be intermediate between that of WDTC and poorly differentiated anaplastic thyroid cancer. J. Surg. Oncol. 2004;86:44-54.

Insular carcinoma of the thyroid in an adolescent: a case report and review of the literature

A 15-year-old girl was referred for a thyroid gland mass, which rapidly enlarged in the brief interval between initial evaluation and surgery. Fine needle aspiration of the mass suggested a diagnosis of papillary thyroid carcinoma. Upon pathological examination of this aggressive tumor, an "insular" pattern of tumor was identified. Insular carcinoma of the thyroid gland is unusual in the pediatric age group, however its aggressive nature and prognosis have important management implications for those physicians involved in the care of affected patients. Aggressive surgical debulking, very close observation of the course of disease, and adjunctive radioiodine therapy may all be indicated as were performed in this case. A description of the pathology of this condition, and a review of the clinical experience with insular carcinoma in childhood and adolescence are presented.

Clonal analysis helps to differentiate aberrant thyroid tissue from thyroid carcinoma

A rare case of multiple aberrant of thyroid tissues in the tongue and lymph nodes of the bilateral neck was studied by immunohistochemistry and molecular clonal analysis to determine whether these tissues represent aberrant ectopic thyroid or metastases of a thyroid carcinoma. The thyroid tissues in the tongue and lymph nodes were all of polyclonal origins, consistent with ectopic thyroid in the tongue and bilateral cervical lymph nodes, rather than malignant thyroid tissues. This case shows that molecular clonal analysis can be used to distinguish aberrant thyroid from metastases of thyroid carcinoma.

Imaging of the thyroid gland

The thyroid gland is critical in regulating metabolic functions including cardiac rate and output, lipid catabolism, skeletal growth, and oxygen and heat production. Thus, patients with hormonally active thyroid abnormalities present with wide-ranging symptoms, requiring an understanding of the gland's hormonal functions. Radiological imaging assesses the pathophysiological affects of abnormal thyroid function as well as important morphological features. Nuclear scintigraphy provides functional information about the gland, whereas cross-sectional imaging-including ultrasound, CT, and MR-provide adjunctive anatomic information. These modalities also provide information about related structures in the neck. The embryology, anatomy, and physiology of the thyroid are discussed; congenital, autoimmune, inflammatory, metabolic, and neoplastic diseases are reviewed; and the diagnostic utility of radiological imaging is addressed.