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Introduction: The thymus normally forms in the neck from the third pharyngeal pouch and descends to its normal position in the mediastinum. Arrest of descent or sequestration of thymic tissue can occur at any point along its path leading to an ectopic thymus which can present as a neck mass, usually in the paediatric age group. Purpose and Case Report: Ultrasound is generally performed in the presence of a neck mass in children. Although a characteristic 'starry sky' appearance of the thymus has been described on ultrasound, it is not considered sufficiently specific and cross-sectional imaging with magnetic resonance imaging is usually performed. On magnetic resonance imaging, the ectopic thymus appears as a homogeneous T1 isointense and T2 hyperintense mass and may actually appear ominous due to the tendency of ectopic thymus to sometimes show diffusion restriction unlike the normal thymus. Subsequent invasive biopsy or surgical removal is usually necessary to rule out a neoplastic lesion. In our observation, the ultrasound appearance of thymus is sufficiently distinctive to be confidently diagnosed as ectopic thymic tissue. This appearance is similar to the high-resolution appearance of an embroidery yarn. The reason most radiologists are not aware of the same is because the normal mediastinal thymus is not usually imaged by ultrasound. Conclusion: An accurate diagnosis on ultrasound would mean avoidance of expensive cross-sectional imaging and invasive biopsy or surgical excision in favour of regular non-invasive follow-up ultrasound scans until the lesion involutes in late childhood. [ABSTRACT FROM AUTHOR]

The thymus, a vital immune organ in humans, plays a crucial role in the differentiation and development of T cells. Its normal development commences around the fourth week of gestation, originating from the ectoderm of the third branchial cleft and the endoderm of the third parotid pouch. By the 7-8th week of gestation, the primary thymus migrates towards the central axis. However, various factors may disrupt this process, leading to congenital anomalies such as incomplete descent of thymus tissue. Persistence of residual thymus tissue can result in the formation of ectopic thymus. Although ectopic thymus is rare in clinical practice, sporadic cases have been reported in the neck or mediastinum, with fewer occurrences in the pericardium, chest wall, axilla, and thyroid gland. It is estimated that ectopic thymus accounts for approximately 0.4% of neck masses, and improper removal may predispose the child to immune deficiencies. This article focuses on a neonatal patient presenting with respiratory failure, where a foreign body was discovered in the oral cavity during weaning from mechanical ventilation. Subsequently, the tumor progressively enlarged postextubation. Surgical excision of the tumor revealed pathological abnormalities upon hematoxylin-eosin (HE) staining, confirming ectopic thymus tissue. B-ultrasound examination confirmed the presence of thymus tissue, and the child's condition improved, leading to hospital discharge. Follow-up assessments showed no evidence of immune deficiency in the child.

Objectives: Ectopic thymic tissue in the subglottis is an extremely rare disease that causes airway obstruction. Few cases reported were accurately diagnosed before surgery. Methods: A case of a 2-year-old boy with airway obstruction caused by a left subglottic mass was reported. The presentation of radiological imaging, direct laryngoscopy and bronchoscopy, pathology, and surgical management were reviewed. An extensive search in PubMed, EMBASE, Web of Science, Google Scholar, and EBSCO of English literature was performed without a limit of time. Results: Besides our case, only six cases were reported since 1987. The definitive diagnosis on these patients were made with the findings of pathology, of which, five were ectopic thymus and two were ectopic thymic cysts. Our case was the only one with a correct suspicion preoperatively. Four cases underwent open surgical resection, and two cases underwent microlaryngeal surgery, while one deceased after emergency tracheostomy. No recurrences were found by six patients during the follow-up after successful treatments. Conclusion: Ectopic thymus is a rare condition, infrequently considered in the differential diagnosis of subglottic masses. Modified laryngofissure may be an effective approach to removing the subglottic ectopic thymus and reconstructing the intact subglottic mucosa.

Migration of the embryonic thymus is thought to be the basis for the formation of ectopic thymic tumors. Thymic ectopy may be a result of the abnormal migration of the third or fourth branchial cleft to the anterior mediastinum during weeks 5--6 of embryonic development. However, ectopic thymic carcinoma has highly nonspecific histologic features and occurs in variable and unpredictable locations making it difficult to diagnose. However, the clinical diagnosis and treatment should not overlook the possibility of ectopic thymic tumors. Here, we report a case of ectopic thymic carcinoma diagnosed as thyroid cancer before surgery occurring in a location consistent with current assumptions. Furthermore, we briefly review the literature on ectopic thymic carcinoma and discuss current diagnostic and treatment approaches. [ABSTRACT FROM AUTHOR]

Background: The thymus gland is a lymphoid organ normally located in the anterior mediastinum. Location abnormalities of the thymus, such as ectopic thymus or the superior herniation of a mediastinal thymus, could be responsible for the occurrence of cervical masses in pediatric patients, raising concerns among clinicians. The knowledge of these conditions is essential for a thorough differential diagnosis and for preventing unnecessary invasive procedures. Methods: Descriptive retrospective series of three patients with a cervical mass, that was later diagnosed as ectopic thymic tissue. Results: The thymus has a unique and distinctive ultrasound appearance that is the keystone to detecting thymic parenchyma in locations other than anterior mediastinum. In selected patients, an accurate ultrasound could be conclusive for the diagnosis, with no need for further and potentially risky procedures. Conclusions: This case series supports the use of ultrasound in both diagnosis and follow-up of thymus location abnormalities, advocating a minimal invasive and conservative approach. [ABSTRACT FROM AUTHOR]

Abstract Background Ectopic 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 presentation We 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. Conclusions The 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.

Background. Intrathyroidal ectopic thymus (IET), a benign lesion due to aberrant thymic migration during embryogenesis, is often discovered incidentally. We aimed to present the ultrasound (US) features, diagnostic methods, and follow-up of IET in children and adolescents. Methods. We searched our database of patients with a nodular thyroid lesion detected by US, between January 2007 and December 2019. In 30/255 (11.7%), IET was diagnosed. Results. The study included 30 patients (20 males/10 females), mean age 5 years (0.1-12.2, median 5.6) with 34 lesions diagnosed by US as 'incidentalomas.' None of the patients had palpable nodules. On US, IET appeared as a hypoechoic lesion, with multiple punctuate internal echoes. 29/34 of lesions had well-defined margins. The most common location of IET was in the middle part (27/34) of the left lobe (19/34). The mean longest diameter at diagnosis was 6.4 mm (2.5-21, median 4.5). Sonographic follow-up was available in 25 patients with 27 lesions. The mean time of observation was 2.7 years (0.3-7.5, median 2.1). While 13/27 cases showed decreased size or regression during follow-up, the other 13 increased in size, and there was no change in size in one. Pubertal progression was associated with both increment and decrease in size of IET. Fine needle aspiration (FNA) was performed in 5 patients and surgery in one. Conclusions. IET should be considered in the differential diagnosis of pediatric thyroid nodules as a cause of FNA and/or surgery. Regular US monitoring can be used safely in the follow-up of this lesion. We present one of the largest series in the literature with long-term follow-up and description of patients' pubertal status. IET prevalence was 11.7% among children and adolescents with a nodular thyroid lesion, higher than that stated in the literature. [ABSTRACT FROM AUTHOR]

Although hyperthyroidism is the most common endocrine disorder in elderly cats, systematic studies investigating the prevalence of thyroid lesions in feline animals are scarce. Our objective was to evaluate morphological changes in the thyroid glands of 61 cats submitted to necropsy without clinical suspicion of hyperthyroidism. Thirteen (13/61 [21.3%]) cats had thyroid enlargement and 54/61 (88.5%) had some histological thyroid changes. Proliferative lesions were histologically seen in 33/61 (54%) cats while non-proliferative lesions were observed in 48/61 (78.7%) cats. Thyroid hyperplasia (18/33 [54.5%]) and cystic adenoma (6/33 [18.2%]) were the most prevalent proliferative changes and lesions with little or no clinical significance (37/61 [60.6%]), degenerative (31/61 [50.8%]) and inflammatory changes (12/61 [19.7%]) were the most common non-proliferative changes. Among cats with proliferative lesions, 16/33 (48.4%) had a proliferation grade ≥A4, a grade previously associated with clinical hyperthyroidism. Although the cats from this study did not have any clinical diagnosis of thyroid disease, it is possible that one or more had some degree of clinically unnoticed thyroid dysfunction. The high prevalence of follicular lesions in this study highlights the importance of a more careful clinical and pathological investigation regarding thyroid diseases in mature and elderly cats., Competing Interests: Declaration of competing interests The authors declared no conflicts of interest in relation to the research, authorship and/or publication of this article., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Ectopic 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 Presentation: We 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.Conclusions: The 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. [ABSTRACT FROM AUTHOR]

Background: The thymus gland is a lymphoid organ normally located in the anterior mediastinum. Location abnormalities of the thymus, such as ectopic thymus or the superior herniation of a mediastinal thymus, could be responsible for the occurrence of cervical masses in pediatric patients, raising concerns among clinicians. The knowledge of these conditions is essential for a thorough differential diagnosis and for preventing unnecessary invasive procedures. Methods: Descriptive retrospective series of three patients with a cervical mass, that was later diagnosed as ectopic thymic tissue. Results: The thymus has a unique and distinctive ultrasound appearance that is the keystone to detecting thymic parenchyma in locations other than anterior mediastinum. In selected patients, an accurate ultrasound could be conclusive for the diagnosis, with no need for further and potentially risky procedures. Conclusions: This case series supports the use of ultrasound in both diagnosis and follow-up of thymus location abnormalities, advocating a minimal invasive and conservative approach.

Abstract Background Thymomas generally arise from the thymus in the anterior mediastinum. Ectopic thymomas arising in the middle mediastinum are rare. We present a case of a thymoma arising from the ectopic thymic tissue in the right paratracheal region. Case presentation The patient was a 67-year-old male who underwent an enhanced-computed tomography examination as preoperative staging for colon cancer. A 20-mm nodule in the right paratracheal region was found incidentally. Fluorodeoxyglucose (FDG) accumulation was detected in this solitary nodule by FDG-positron emission tomography, mimicking an enlarged, possibly malignant lymph node. The tumor was removed by thoracoscopic surgery, and a postoperative pathological diagnosis of type AB thymoma was made. Foci of ectopic thymic tissues were found adjacent to the thymoma. The patient was disease-free and without recurrence 2 years postoperatively. Conclusions Including the present case, 13 cases of ectopic paratracheal thymoma have been reported in the English literature, all of which were found on the right side of the paratracheal region. Although ectopic thymomas in the paratracheal region are rare, thymomas may be considered as a differential diagnosis for a paratracheal nodule.

Objectives: Ectopic thymus is rare and can be a diagnostic challenge. This study evaluated the management of children radiographically diagnosed with ectopic cervical thymus.Methods: A retrospective review of 100 patients was performed. Data related to clinical presentation, radiological imaging, pathology, and management were collected. Changes in lesion volume were tracked over time. Clinical characteristics were compared based on lesion location in the neck using analysis of variance modelling.Results: There were 115 lesions with radiographic features of ectopic cervical thymus (15 children had bilateral lesions). Diagnosis was based on ultrasound in 98% of patients, magnetic resonance imaging in 18%, and computed tomography in 11%. Mean (SD) follow-up duration was 2 (2.2) years. Forty-four percent (51/115) of lesions involved the thyroid gland, 29% (33/115) were in the central neck but separate from the thyroid, 18% (21/115) had mediastinal extension, and 8% (9/115) involved the submandibular region. Location was unclear for two patients. Submandibular lesions were on average 12.4 cm3 larger (95% CI, 8.2, 16.6) than mediastinal lesions at diagnosis, P ≤ .001. Volume of thymic tissue decreased over time, from a mean (standard deviation [SD]) volume of 4.3 cm3 (9.2) at initial ultrasound to 2.7 cm3 (6.1) at final ultrasound (paired t-test, P = .008). Only two patients required surgery: one for compressive symptoms, and the other to rule out malignancy.Conclusion: Ninety-eight percent of children with ectopic cervical thymus were managed conservatively without issues. We propose a classification system based on location to ease communication among clinicians and to help follow these lesions over time.Level Of Evidence: 4, case series Laryngoscope, 130:1577-1582, 2020. [ABSTRACT FROM AUTHOR]

Objectives: The aim of our study is to report a case of a child with subglottic thymus that was suspected during diagnostic work-up for severe airway obstruction, excised surgically and confirmed with final histopathological examination. Moreover, we performed a narrative literature review to outline clinical and diagnostic features of this rare condition and to report suggestions for the management of subglottic masses. Methods: We report the case of a 7-month-old boy who was admitted to our Pediatric Airway Team Unit due to a history of worsening biphasic stridor and recurrent episodes of upper airway obstruction. The successful diagnostic work-up and a narrative literature of analogous cases of subglottic thymus were reported. Results: Ectopic thymus is a very rare condition in which thymic tissue is found outside the normal pathway of its embryonic migration. It usually presents as a cystic or, more rarely, solid mass, showing an indolent course toward spontaneous involution. In some cases, however, it becomes symptomatic exerting compression on surrounding vital structures. Due to its rarity, the initial diagnosis is normally mistaken with inflammatory diseases or malignancies and the definitive diagnosis is only achieved after histological examination of the excised specimen. To our knowledge, only four other cases of subglottic ectopic thymic tissue have been reported in the English literature so far and the diagnosis has never been suspected preoperatively. Conclusion: It is mandatory to consider ectopic thymic tissue in the differential diagnosis in children presenting with airways obstruction in order to prevent unnecessary, extensive, and exploratory surgery. [ABSTRACT FROM AUTHOR]

Pharyngeal ectopic thymus is a rare cause of pharyngeal masses and is rarely considered in the differential diagnosis of neck and head masses in children. In this paper, the case of an infant with a pharyngeal ectopic thymus is presented and our intraoral surgical approach in the patient's treatment is described. [ABSTRACT FROM AUTHOR]

Thyroid nodules with ultrasound (US) cancer risk features and extra-thyroid lesions suggesting malignant lymph nodes, require prompt diagnosis, especially in children. The US pattern of intrathyroidal ectopic thymus (IET) can strongly suggest papillary thyroid carcinoma (PTC). The extra-thyroid ectopic thymic tissue (EET) can mimic pathological lymph nodes in US. The aim of the study has been to demonstrate US features and diagnostic methods, allowing finally to confirm the presence of IET and EET in children. The US and elastographic features of 16 ectopic thymic tissue (ET) lesions were analyzed so as to describe the typical characteristics of ET and to define the best method to differentiate ET and malignant lesions. Among 16 analyzed lesions, 11 lesions were IET, and 5 were EET adjacent to the thyroid connective tissue capsule. Most of IET were located in the middle part of the right lobe and were fusiform or oval in shape. All the lesions were solid, hypoechoic, and heterogeneous with bright internal echoes. Among IET, 73% of lesions had well- or very well-defined margins. In strain elastography of IET lesions, the strain ratio was similar in all lesions, and its value ranged from 0.95 to 1.09. Despite the low prevalence of IET and cervical EET, clinicians and radiologists should be aware of US characteristics of such lesions. The confirmation of their benign character is absolutely required. Elastography is a useful tool to initially differentiate PTC and IET. However, due to high risk of malignancy in thyroid lesions in children, similarity of US features of PTC and IET, and due to the possibility of malignancy in ET, only cytological evaluation provides definitive diagnosis.

Thyroid nodules with ultrasound (US) cancer risk features and extra-thyroid lesions suggesting malignant lymph nodes, require prompt diagnosis, especially in children. The US pattern of intrathyroidal ectopic thymus (IET) can strongly suggest papillary thyroid carcinoma (PTC). The extra-thyroid ectopic thymic tissue (EET) can mimic pathological lymph nodes in US. The aim of the study has been to demonstrate US features and diagnostic methods, allowing finally to confirm the presence of IET and EET in children. The US and elastographic features of 16 ectopic thymic tissue (ET) lesions were analyzed so as to describe the typical characteristics of ET and to define the best method to differentiate ET and malignant lesions. Among 16 analyzed lesions, 11 lesions were IET, and 5 were EET adjacent to the thyroid connective tissue capsule. Most of IET were located in the middle part of the right lobe and were fusiform or oval in shape. All the lesions were solid, hypoechoic, and heterogeneous with bright internal echoes. Among IET, 73% of lesions had well- or very well-defined margins. In strain elastography of IET lesions, the strain ratio was similar in all lesions, and its value ranged from 0.95 to 1.09. Despite the low prevalence of IET and cervical EET, clinicians and radiologists should be aware of US characteristics of such lesions. The confirmation of their benign character is absolutely required. Elastography is a useful tool to initially differentiate PTC and IET. However, due to high risk of malignancy in thyroid lesions in children, similarity of US features of PTC and IET, and due to the possibility of malignancy in ET, only cytological evaluation provides definitive diagnosis. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study was to investigate the ultrasound characteristics and clinical significance of slightly hyperechoic lesions, referred to as phantom nodules, in the perithyroidal area in patients. Materials and Methods A total of 128 patients who underwent thyroidectomy with central neck lymph node dissection at Kuma Hospital in Hyogo, Japan were included in the study. We detected 16 phantom nodules during preoperative ultrasound examinations, defined as slightly hyperechoic masses located in the perithyroidal areas, in 13 of these 128 patients (10.2%; mean age: 55.6 years, range: 36–75 years). Results All phantom nodules were located in the caudal region of the thyroid gland, and the mean maximum dimension was 7.2 mm. 12 of the 16 nodules were round or oval, while the remaining 4 were fusiform and molded by the surrounding tissue. All nodules were well-defined, solid, homogeneous, hyperechoic masses. No speckled echo pattern, internal linear echo, or vascular flow signal was observed. All 4 nodules subjected to histological examination were composed of ectopic thymic tissue. In 2 of these 4, the parenchyma was severely involuted and almost entirely replaced by adipose tissue. Conclusion To the best of our knowledge, this is the first report wherein some of the detected hyperechoic perithyroidal masses were composed of ectopic thymic tissue, and some were primarily composed of adipose tissue that completely replaced involuted ectopic thymic tissue. The results of the study suggest that these so-called phantom nodules are clinically insignificant and do not require fine needle aspiration cytology or further investigation.

Ectopic intrathyroidal thymus tissue is rare. Mostly it is seen in childhood as an asymptomatic thyroid nodule. It can be easily misdiagnosed as a benign or malignant thyroid nodule. Like thymus, it may regress in time. Ectopic thymus tissue can rarely develop to thymoma or thymic carcinoma. Intrathyroidal ectopic thymus tissue has similar sonographic features to thymus and should be kept in mind to avoid unnecessary diagnostic and surgical intervention. [Med-Science 2015; 4(2.000): 2224-8]

Introduction: Ectopic thymic tissue can arise as an asymptomatic neck mass, which may be detected on imaging studies. The aim of this study was to determine the incidence of ectopic thymic tissue in paediatric FNAs and to the correlate clinical, radiological and cytomorphological findings. Methods: FNAs in children with neck and mediastinal lesions performed between January 2012 and July 2016 were reviewed for cases of ectopic thymus. These were then evaluated and correlated with the cytology findings. Results: Of 739 FNAs, 13 (1.8%) cases from 11 patients showed ectopic thymic tissue. The targeted lesions were in the thyroid (n = 7), submandibular region (n = 1), superior mediastinum (n = 1) and paratracheal region (n = 1). The most common indication was for microcalcifications concerning for papillary thyroid carcinoma on ultrasound (n = 6). Imaging findings included fusiform lesions with linear and punctuate bright echoes. The cytology evaluation showed small lymphocytes with discohesive epithelioid cells in most cases, and proteinaceous fluid in the cystic case. There were rare macrophages and Hassall's corpuscles. Flow cytometry and/or immunostains were performed in all cases, supporting thymic origin. Conclusion: Ectopic thymic tissue is rarely present as a neck mass or thyroid nodule on FNA biopsy. The ultrasound imaging findings reveal a well‐defined fusiform lesion with punctate bright echoes that could be misinterpreted as papillary thyroid carcinoma. The aspirates show a small lymphoid population, immunophenotypically compatible with thymic T‐cells, in addition to scattered epithelial cells. Therefore, knowledge of the typical ultrasonographic and cytopathological features can help make a definitive diagnosis and avoid more invasive procedures in paediatric patients. [ABSTRACT FROM AUTHOR]

Background: We have reported three cases of incidental findings of solid cell nests, ectopic thymus with parathyroid tissue and thyrolipoma in thyroidectomy specimens. These patients presented clinically as nodular thyromegaly and were directed for FNAC. Ultrasound findings were suggestive of nodular goiter and on histopathology revealed features compatible with nodular goiter along with incidental findings of solid cell nests, ectopic thymus with parathyroid tissue and thyrolipoma. Differential diagnosis of thyroid nodules should include these rare diagnostic findings which create confusion in thyroid pathology as they mimic malignancies both clinically and histologically and also because neoplasms may arise in the background of these rare findings. Objectives: To analyze clinicopathological findings in thyroid specimens, to correlate with Ultrasonography (USG), Fine needle aspiration cytology (FNAC), hormonal assay and immunohistochemistry. Materials and methods: All the specimens were analyzed and routinely processed for histopathology and stained with haematoxylin and eosin. Results: Incidental associated findings were noted in three cases composed of solid cell nests, ectopic thymus with parathyroid tissue and thyrolipoma. Conclusion: Three incidental and relatively unusual findings of solid cell nests, ectopic thymus with parathyroid tissue and thyrolipoma were diagnosed on histopathology. These lesions of thyroid gland must be differentiated from close mimickers including both non-neoplastic and neoplastic lesions clinically, radiologically and microscopically. Though benign and rare, these incidental findings should be thought of in all the thyroid specimens to avoid confusion with neoplastic thyroid pathology and also because they carry a potential risk for developing into neoplastic lesions. [ABSTRACT FROM AUTHOR]

Background: During gestation, the primordial thymus migrates from the pharynx to the anterior mediastinum, thus thymic tissue can remain at any point along this path. Intrathyroidal thymic remnants are rare, and their sonographic patterns have only recently been described. This retrospective study presents the sonographic appearance of ectopic intrathyroidal thymus and emphasizes the role of sonography in order to avoid misdiagnosis. Methods: The population consisted of 42 children, 3.5-14 years old, who had a thyroid sonogram performed due to a positive family history or symptoms indicative of thyroid disease, and ectopic intrathyroidal thymus was recognized. Results: In all patients, the same pattern was revealed: a fusiform intrathyroidal lesion, with no mass effect, homogeneously hypoechoic, with diffuse bright internal echoes. The similarity to the characteristic sonographic pattern of the normal mediastinal thymus was crucial for the diagnosis of ectopic intrathyroidal thymic tissue. In 8 cases, a normal elongated thymus was found connected to the thyroid with an accessory lobe embedded in the lower thyroid pole. The above sonographic appearances mimicked a thyroid nodule. Conclusions: Awareness of the sonographic patterns of the ectopic intrathyroidal thymus is mandatory to avoid misdiagnosis. In most cases, further investigation is unnecessary, but sonographic follow-up should be recommended. [ABSTRACT FROM AUTHOR]

Introducción. El objetivo principal de nuestro trabajo es el estudio histológico del desarrollo del timo humano entre la 5ª y la 8ª semana de gestación. Describimos varios términos embriológicos poco usados como: timo secundus, descensus thymi (la base embriológica para situar el timo en la garganta), ductus timicus (la base embriológica para el defecto innato llamado conducto timofaríngeo con posibilidad de formar un quiste). Material y método. Nuestras observaciones se basan en la investigación de 18 embriones humanos entre la 6ª y la 8ª semana de gestación. Resultados. La base del timo es común con la base de las glándulas paratiroideas. Es comparable con las bolsas faríngeas (saccus pharyngeus) en los embriones largos de 8 a 9 mm. La proliferación endodermal del epitelio en el tercer foco faríngeo (focus faringeus 3) es muy visible. La parte craneal y la parte dorsal son la base de origen de las glándulas paratiroideas inferiores. La parte caudal y la parte ventral son la base para el timo. Hemos observado también la notable proliferación del epitelio en la segunda bolsa faríngea, llamado por algunos autores Timo secundus. En nuestra opinión, en el ser humano no se forma un timo funcional en este lugar y la proliferación del epitelio en la mayoría de los casos, se detiene pronto. Conclusión. En este trabajo ofrecemos una vista general sobre la importancia clínica del desarrollo del timo y la descripción de los defectos innatos más frecuentes del mismo. Introduction. The aim of our morphological study is to describe the development of human thymus from 5th up to 8th week after fertilization in the context of its phylogenesis. We explicate some of the “forgotten” embryological terms with respect to their functions in thymic development, such as “thymus secundus”, “descensus thymi” (an embryological basis for cervical thymus) and “ductus thymicus” (an embryologic basis for a congenital anomaly called thymopharyngeal duct with possible thymic cyst). Material and methods. Our findings are based on the study of 18 human embryos from 6th to 8th week of development. Results. The first primordia of the thymus and parathyroid glands within the endoderm of pharyngeal pouches can be seen in 8 to 9 mm crown-to-rump-length stages. The most evident epithelial proliferation is visible in the paired third pharyngeal pouch (saccus pharyngeus tertius): the cranial dorsal part of pharyngeal pouch initiates the inferior parathyroid gland and the caudal ventral part of the pouch gives rise to the epithelial thymus. We found an obvious endodermal epithelial proliferation also in the second pharyngeal pouch. Some authors depict this proliferation as “thymus secundus”, but the proliferation of endoderm close down and the functional second thymus does not develop in human embryos. Conclusion. In our work we also review the clinical significance of early thymus development, as well as the most common developmental anomalies of thymus.

Migration of the embryonic thymus is thought to be the basis for the formation of ectopic thymic tumors. Thymic ectopy may be a result of the abnormal migration of the third or fourth branchial cleft to the anterior mediastinum during weeks 5-6 of embryonic development. However, ectopic thymic carcinoma has highly nonspecific histologic features and occurs in variable and unpredictable locations making it difficult to diagnose. However, the clinical diagnosis and treatment should not overlook the possibility of ectopic thymic tumors. Here, we report a case of ectopic thymic carcinoma diagnosed as thyroid cancer before surgery occurring in a location consistent with current assumptions. Furthermore, we briefly review the literature on ectopic thymic carcinoma and discuss current diagnostic and treatment approaches.

A 21-year-old female presented with a history of slowly enlarging nodular painless mass on the right side in the anterior part of the neck. The patient was asymptomatic except for cosmetic disfigurement. Thyroid function test results were within normal limits. On fine needle aspiration cytology, it was diagnosed as colloid nodule. A right hemithyroidectomy was performed in view of cosmetic disfigurement; histopathological examination of the excised specimen revealed ectopic thymic tissue adjacent to thyroid. This case is reported to emphasize the possible clinical and surgical presentation of this rare entity.

Palpable tumors in children are a common reason for consulting a radiologist. The origin of these lesions varies widely, and although they are common, classic radiology books do not cover some of them. This series of two articles aims to review the clinical and radiological characteristics of a selection of palpable tumors in children that radiologists need to be familiar with., (Copyright © 2022 SERAM. Published by Elsevier España, S.L.U. All rights reserved.)

Objectives: Ectopic thymic tissue in the subglottis is an extremely rare disease that causes airway obstruction. Few cases reported were accurately diagnosed before surgery., Methods: A case of a 2-year-old boy with airway obstruction caused by a left subglottic mass was reported. The presentation of radiological imaging, direct laryngoscopy and bronchoscopy, pathology, and surgical management were reviewed. An extensive search in PubMed, EMBASE, Web of Science, Google Scholar, and EBSCO of English literature was performed without a limit of time., Results: Besides our case, only six cases were reported since 1987. The definitive diagnosis on these patients were made with the findings of pathology, of which, five were ectopic thymus and two were ectopic thymic cysts. Our case was the only one with a correct suspicion preoperatively. Four cases underwent open surgical resection, and two cases underwent microlaryngeal surgery, while one deceased after emergency tracheostomy. No recurrences were found by six patients during the follow-up after successful treatments., Conclusion: Ectopic thymus is a rare condition, infrequently considered in the differential diagnosis of subglottic masses. Modified laryngofissure may be an effective approach to removing the subglottic ectopic thymus and reconstructing the intact subglottic mucosa., (Copyright © 2021 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.)