Intrathyroidal Thymic Tissue Research Articles

Spindle epithelial tumor with thymus-like elements (SETTLE): a diagnostic challenge with distinct therapeutic implication; case report

Spindle epithelial tumor with thymus-like elements (SETTLE) is a rare malignant neoplasm of the thyroid gland which is believed to arise from intrathyroidal thymic tissue. It predominantly affects young adults and children presenting with a thyroid mass of variable duration and rarely occurs in adults. It has a high overall survival with a tendency for delayed metastasis. SETTLE is a biphasic lobulated tumor composed of spindle shaped cells along with glandular formations seen on histopathological examination. Despite its typical morphology it is commonly misdiagnosed on histopathology due to its rarity and overlapping morphology with other close mimics such as a carcinoma, synovial sarcoma and thymoma. Herein we report such a case occurring in a middle aged female presenting with a neck mass. She had an initial diagnosis of metastatic poorly differentiated squamous cell carcinoma possibly with an orophayngeal primary in view of co expression of CK, p40 and p16 on immunohistochemistry. The patient underwent surgical resection with modified neck dissection. On review at our hospital it was diagnosed as SETTLE and she remains disease free after a follow-up period of 1 year. Diligent histopathological examination espoused with a judicious panel of IHC markers in conjunction with clinicoradiological findings forms the mainstay of diagnosis. Diffuse and strong p16 immunoexpression has not been documented or evaluated in literature so far, and needs to be explored for its diagnostic utility in this rare entity.

Ectopic intrathyroidal thymic tissue in an adult patient: a case report and review of the literature

BackgroundEctopic intrathyroidal thymic tissue is a rare diagnosis, specifically in adults. Such ectopic tissue is usually misdiagnosed as benign or malignant thyroid lesions and is mainly investigated by ultrasonography and pathologic examination.Case presentationWe present the case of an adult 31-year-old Persian female patient with a cervical mass and no other significant medical history. The lesion had hypo- to isoechoic features on sonographic imaging, and needle aspiration examination revealed lymphoid cells suspicious of lymphoid malignancies. However, pathologic examination after resection of the lesion showed normal thymic tissue.ConclusionsThe rare entity of ectopic thymic tissue within the thyroid gland in adult patients requires meticulous examination by clinicians, radiologists, and pathologists to diagnose the condition with high accuracy and plan appropriate management.

Echographic findings in ectopic intrathyroidal thymic tissue in children. A systematic review

Intrathyroidal ectopic thymic tissue (IETT) is an indulgent, unusual entity and is part of the differential diagnosis of thyroid nodules in the pediatric population. Because of the low prevalence of IETT, the diagnosis may be difficult. Awareness of this diagnosis is definitive to avoid surgical interventions. The aim of this study was to review the literature on the echographic characteristics of IETT. We conducted a search of Ovid, PubMed and the virtual health library.A total of 619 patients with a mean age of 6.2 years old were included. IETT was located in the lower portion of both of the thyroidal lobes in 556 children, the echographic shape was reported for 173 patients, with the fusiform shape as the most representative, the appearance of the IETTs was reported for 121 patients, the most common was the hypoechogenic pattern with multiple internal echogenic foci. The average lesion diameter was 5.53 mm, and Doppler findings reported a hipovascular pattern in 56% of the lesions.In conclusion, IETT is an infrequent entity; nonetheless, it must be considered in the differential diagnosis of neck nodules in children and should be study and follow with echography to avoid unnecessary surgery.

Cytomorphologic findings of thyroid carcinoma showing thymus-like (CASTLE) differentiation: A case report

Abstract Introduction/Objective Thyroid carcinoma showing thymus-like differentiation also known as intrathyroidal thymic carcinoma is a rare thyroid neoplasm arising from either an ectopic intrathyroidal thymic tissue or from remnants of thymobranchial pouches. On fine needle aspiration (FNA) its diagnosis can be challenging due to overlapping morphologic features with other aggressive thyroid carcinomas. Methods/Case Report A 31-year-old female consulted for 6-month history of neck swelling and tenderness. Thyroid ultrasound demonstrated a 2.6 x 2.5 x 2.1 cm nodule in the right lobe with punctate calcifications. FNA showed cellular smears composed of loosely cohesive and single basaloid neoplastic cells exhibiting significant cellular and nuclear pleomorphism. Focal squamous differentiation with keratinization was noted on the cell block sections. Immunocytochemical stains showed that the tumor was positive for cytokeratin AE1/AE3, p40, p63, CD117 and CD5 consistent with intrathyroidal thymic carcinoma. The Ki67 proliferative index was approximately 40%. A right thyroidectomy with central neck dissection confirmed the diagnosis and showed a 3.0 cm tumor with invasion into skeletal muscle, lymphovascular invasion and positive lymph nodes. The patient completed adjuvant radiotherapy and remain in remission at 3-months follow-up. Results (if a Case Study enter NA) NA Conclusion Intrathyroidal thymic carcinoma is a rare thyroid neoplasm that frequently shows squamous differentiation and therefore overlaps with papillary thyroid carcinoma with squamous morulae, squamous cell carcinoma and anaplastic carcinoma. The coexpression of squamous markers together with CD5 and CD117 allows the recognition of CASTLE on FNA samples.

Issue Highlights-July 2021.

Issue Highlights-July 2021.

Intra-Thyroidal Thymic Tissue May Display Radiological Features Suggestive of Malignancy - A Case Report

Intra-Thyroidal Thymic Tissue May Display Radiological Features Suggestive of Malignancy - A Case Report

Intrathyroidal thymic tissue in children: Avoiding unnecessary surgery.

Intrathyroidal thymic tissue may be misinterpreted as a thyroid lesion in children, leading to invasive tests or resection. We sought to describe the characteristic imaging features of these lesions and to evaluate the safety of non-operative management. A retrospective review of all patients less than 18years old with intrathyroidal thymic tissue from 2000 to 2016 was performed. Data collection included patient demographics, imaging results, interventions, and outcomes. Eleven patients were identified using institutional radiology and pathology databases. Median patient age and lesion size at presentation were 5years old (range 2 to 8years old) and 0.9cm (range 0.4 to 9.2cm), respectively. Six lesions were incidentally identified, six were left-sided, and the most common location was the lower pole. Ultrasonographic features were reproducible and included well demarcated (10/11), hypoechoic lesions (11/11), containing punctate/linear internal echoes (11/11), and occasional mild hypervascularity (6/11). All cases demonstrated interval size and echotexture stability over a median surveillance period of 3years (range 1 to 8years). While 9 patients were simply observed, the first patient in this series underwent excision, while another had a fine needle aspiration to confirm pathology. Study of diagnostic test, Level IV. Intrathyroidal thymic tissue has typical clinical and sonographic characteristics which allow for appropriate diagnosis and avoids thyroid resection.

Ectopic Intrathyroidal Thymic Tissue Mimicking Thyroid Nodules in Children.

Ectopic intrathyroidal thymic tissue is a benign lesion of nonthyroid origin occasionally found in the pediatric thyroid gland. Accurate diagnosis of such lesions is critical to avoid unnecessary biopsy or surgery. Twelve children referred to our center for the concern of thyroid nodules were found to have intrathyroidal thymic tissue. Most of the lesions had a classic sonographic appearance of a hypoechoic mass with sharp margins and multiple focal internal nonshadowing echogenicities identical to thymic tissue. Sonography and, in select cases, fine-needle aspiration can be used to diagnose benign thymic tissue within the thyroid and avoid unnecessary surgery.

Concurrent intrathyroidal thymus and parathyroid in a patient with papillary thyroid carcinoma: a challenging diagnosis.

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.

Flow Cytometric Detection of Intrathyroidal Ectopic Thymic Tissue in Thyroid FNA Samples: Report of Three Cases

Flow Cytometric Detection of Intrathyroidal Ectopic Thymic Tissue in Thyroid FNA Samples: Report of Three Cases

Intrathyroidal Ectopic Thymic Tissue Mimicking Thyroid Cancer in Children

To increase awareness of the important differential diagnosis between thyroid cancer and intrathyroidal ectopic thymic tissue when performing neck ultrasound (US) in pediatric patients. We report 2 cases of intrathyrodal thymic tissue that were initially referred as possible papillary thyroid cancer (PTC). US and cytologic features of these lesions are described, and the distinguishing US characteristics of intrathyroidal thymic tissue versus PTC are discussed. Two pediatric patients who underwent thyroid US were diagnosed with thyroid nodules suggestive of PTC. The suspected lesions in both patients exhibited an echo texture identical to the normal thymus gland. Fine-needle aspirate (FNA) biopsy of the nodule in the first case revealed numerous lymphocytes with positive immunocytochemical staining for CD3, confirming a T cell phenotype. The second patient underwent follow-up US imaging 8 months later that showed stability of the intrathyroidal nodule. Intrathyroidal ectopic thymic tissue can be mistaken for PTC as both conditions have similar US features. Increased awareness of this unique mimicry may help to avoid unnecessary invasive investigations and surgery in these young patients.

Intrathyroidal thymic tissue mimicking a thyroid nodule in a 4‐year‐old child

A 4 year-old girl was referred for CT of her neck for suspected submental lymphadenopathy and was found to have an incidental low-attenuation thyroid mass. Subsequent thyroid ultrasound showed a heterogeneous thyroid mass with punctate areas of increased echogenicity. Cytologic examination was consistent with ectopic intrathyroidal thymic nodule. We review the presentation of ectopic thymic tissue, especially in the thyroid gland.

Intrathyroidal ectopic thymic tissue may mimic thyroid cancer: a case report

Ectopic intrathyroidal thymus tissue that may be present as a thyroid nodule is rarely reported. We present a case of a 4-year-old boy with a solitary thyroid nodule. Real-time thyroid ultrasound showed a calcified nodule in the right lobe. Complete blood count, serum calcitonin, and thyroglobulin concentration were normal and antithyroid antibodies were negative. Fine-needle aspiration (FNA) biopsy was revealed as inadequate for cytological examination. During his follow-up, nodular enlargement was found, and the patient was subjected to surgical total excision of the right lobe of the thyroid gland. Pathological examination showed an ectopic intrathyroidal thymus tissue. In childhood, ectopic intrathyroidal thymus tissue can present as an enlarging microcalcified thyroid nodule that may mimic thyroid cancer and may grow during follow-up.

Intrathyroidal Thymic Tissue in an Adult

Sir, Intrathyroidal thymic tissue is a rare entity and is usually found in the prepubertal pediatric population. 1 Adult cases of intrathyroidal thymic tissue are exceedingly rare. We present the case of a 31-year-old woman with a right thyroid papillary carcinoma and left intrathyroidal heterotopic thymic tissue. A 31-year-old woman was referred for evaluation of a right lobe of thyroid enlargement. A thyroid function test revealed decreased serum thyrotropin (0.01 μIU/mL; normal range, 0.35 to 5.50 μIU/mL) and elevated free thyroxine (30.42 pmol/L; normal range, 11.5 to 22.7). All other parameters were normal. Ultrasonography demonstrated a hypoechoic mass with an illdefined margin and multiple calcifications in the upper pole of the right thyroid lobe. Cytopathologic findings of fine needle aspiration from the right lobe of the thyroid were compatible with papillary carcinoma. A pre-contrast computed tomography (CT) scan revealed a thyroid mass with an ill-defined mar gin and heterogeneous density in the upper pole of the right lobe and a small hypoattenuated nodule in the upper pole of the left lobe (Fig. 1A). A post-contrast CT scan demonstrated heterogeneous enhancement of the right lobe of the thyroid mass and no enhancement of the left lobe of the thyroid nodule. A total thyroidectomy was performed. Grossly the cut surface of the right lobe of the thyroid showed a well-circumscribed, whitish solid nodule measuring 1.5×1.4 cm. The left lobe of the thyroid revealed a whitish-yellow, well demarcated nodule measuring 0.5 cm in maximum dimension. Histopathologic examination revealed the presence of a papillary carcinoma in the right lobe and heterotopic thymic tissue in the left lobe (Fig. 1B). The heterotopic thymic tissue of the left lobe consisted of mature adipose tissue, lymphoid tissue with outer cortex and inner medulla, and Hassall corpuscles (Fig. 1C). Small quantities of thyroid follicular epithelial cells were also embedded in the adipose tissue of the heterotopic thymic tissue. Various tissues adjacent to the thyroid can mimic a nodule and should be distinguished from true thyroid nodules. Of these tissues, thymic tissue is probably the most common. Aberrant thymic tissue may be found in the neck in up to 20% of the general population; however, intrathyroidal heterotopic thymic tissue is rare

Ectopic intrathyroidal thymus-Rare finding in an adult

Infrequent occurrence of ectopic intrathyroidal thymic tissue caused by maldescent during early embryologic development is reported. It was incidentally detected during the gross examination of right thyroidectomy specimen of a 27 year old female.

Intrathyroidal Thymic Tissue Surrounding an Intrathyroidal Parathyroid Gland, the Cause of a Solitary Thyroid Nodule in a 6-Year-Old Boy

Ectopic intrathyroidal thymic tissue is a rare occurrence; parathyroid glands sometimes occur in an intrathyroidal location, but this is uncommon. We report a 6-year-old boy who was noted to have a solitary thyroid nodule on ultrasound. A hemithyroidectomy was performed, and histological investigation revealed that the nodule consisted of ectopic intrathyroidal thymus tissue surrounding a well-defined parathyroidal gland. This condition is an exceedingly rare cause of a thyroid nodule, but intrathyroidal thymic tissue should probably be included in the differential diagnosis of solitary thyroid nodules.

A Six-Year-Old Boy with a Suspicious Thyroid Nodule: Intrathyroidal Thymic Tissue

Ectopic intrathyroidal thymus tissue that forms mass lesions as a consequence of aberrant thymic migration during embryogenesis is rarely reported in the literature. We present the case of a 6-year-old boy with a right thyroid nodule and bilateral cervical lymph nodes. Thyroid hormone, antibodies, and routine chemistry tests were normal. Real-time thyroid ultrasound showed a right calcified nodule measuring 8 x 5 x 7 mm and multiple bilateral cervical lymph nodes. I131 scan showed mild decreased uptake in the right upper lobe. On fine-needle aspiration biopsy we discovered an atypical lymphoid proliferation that was suspicious, although not diagnostic, of a lymphoma. Immunostain for calcitonin was negative. Flow cytometry of the thyroid nodule aspirate demonstrated an abnormal polyclonal T cell population with dual expression of CD4 and CD8, and a subpopulation of cells that expressed TdT suggesting the possibility of lymphoblastic lymphoma. DNA analysis, as well as polymerase chain reaction for T cell and B cell gene rearrangement, did not demonstrate changes in the gene for the heavy chain of immunoglobulin of B cells and gamma chain of the T cell receptor. Lymph node aspirate showed unremarkable T and B lymphoid cells. The diagnosis of ectopic intrathyroidal thymus was made after the operation. Ectopic thymus tissue should be considered in the differential diagnosis of thyroid masses, especially in children.

Intrathyroidal thymic tissue: an autopsy study in fetuses with some emphasis on pathological implications.

Fifty-eight human thyroid glands obtained at autopsy from fetuses with proven retrosternal thymus were systematically studied for the presence of intrathyroidal thymic tissue. The latter was found in one thyroid lobe in each of three fetuses (5.1%). It was located in a subcapsular position in two cases (3.4%) and lying deep in thyroid tissue in one (1.7%). Our findings would support a IV-V pharyngeal pouch origin for some accessory thymic tissue and would provide an explanation of the histogenesis of intrathyroid thymomas.