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Subglottic haemangioma presents as progressive obstruction in the neonatal and infantile airway, with a soft lesion seen during endoscopy. Diagnosis is based on macroscopic findings, biopsy is not usually performed and propranolol is first-line treatment. In contrast, ectopic thymus is a rare differential diagnosis for subglottic mass made by histopathological examination after excision or autopsy. In this article, we present a case of an infant with a subglottic lesion with endoscopic features consistent with haemangioma. After initial clinical response to propranolol, the patient represented with progressive stridor no longer responding to therapy. Open excision of the lesion was performed, and histopathology revealed ectopic thymus tissue. In this case, ectopic thymus tissue mimicked the presentation of subglottic haemangioma, and confirmation bias persisted due to an apparent initial clinical response to treatment with propranolol. In cases of subglottic mass refractory to medical treatment, excision of the lesion should be considered.

Background: Intrathyroidal ectopic thymus (IET) can be misdiagnosed as thyroid nodules. Purpose: The purpose of this study is to evaluate the sonoelastographic findings of IET in pediatric population. Methods: Twelve children who had been examined with ultrasound (US) and strain elastography between December 2012 and December 2019 were included in this retrospective study. The patients’ demographics and ultrasonographic findings, including the location, margin, shape, diameters, volume, structure, vascularity, and elastography values of the lesions were evaluated. Results: Twelve lesions were detected in 12 asymptomatic patients (3 females and 9 males) with a mean age of 4.67 ± 2.27 years. The most common location of the IET was in posterior part and middle third of thyroid, and the most common appearance on US was a well-defined, ovoid-shaped, and predominantly hypoechoic solid lesion with punctate/linear branching hyperechogenities. The lesions were mostly hypovascular on Doppler US. The mean strain ratio on elastography was found to be 1.10 ± 0.04. In the follow-up of 7 patients with available information, there was no significant change in size or appearance of IET on US. Conclusion: IET should be considered in the differential diagnosis of the lesions within the thyroid. The first step to accurately diagnose an IET is to consider it in the differential diagnosis. In addition to US, strain elastography findings can be used to distinguish IETs from papillary thyroid cancers which can have similar US appearance, and help avoid unnecessary biopsies.

Carcinoma showing thymus-like elements (CASTLE) is an extremely rare malignant tumor of the thyroid gland and soft tissues of the neck with favorable prognosis. Histological features of the CASTLE are similar to thymic carcinoma, and it is assumed that it arises from the ectopic thymic tissue or the remnants of branchial pouches. The optimal treatment strategy is still uncertain because of the rarity of the tumor. The mainstay of treatment is surgery. The role of other modalities is unclear. We present a case report of a patient with locally advanced CASTLE of the thyroid gland who was not suitable for surgery and underwent radical radiotherapy with subsequent achievement of complete remission. We also present a literature review.

Ectopic thymic tissue is an unusual finding that is generally asymptomatic. We present a case series of five pediatric patients with cervical ectopic thymuses. In two patients, the ectopic thymic tissue was symptomatic, and in three patients, it was an incidental finding. We highlight the need to include this anomaly in the differential diagnosis for a pediatric neck mass. We also propose observation, rather than surgical excision, as the treatment of choice for asymptomatic cervical ectopic thymus.

Ectopic cervical thymus is a rare congenital anomaly, which results because of the failure of complete descent of the thymus. They are incidental findings in the young and may disappear during the early years of life; however, they have rarely been described in adults. Some of them may undergo hyperplasia or neoplastic transformation and become visible or cause symptoms. We report two rare cases of incidentally detected cervical thymic tissue in adults. In one case, the thymic tissue was seen adjacent to a parathyroid adenoma of the left inferior parathyroid gland. In the other, it was seen adjacent to the left inferior parathyroid gland in a case of papillary thyroid carcinoma. In both these cases, the ectopic thymic tissue was diagnosed as a result of pathological examination, not clinically by macroscopic appearance during operation or radiological evaluation. The finding needs to be noted as these ectopic foci can occasionally give rise to hyperplasia and neoplasms of the thymus.

To present the sonographic follow-up of intrathyroidal ectopic thymus (IET) in children and adolescent patients. Out of the 507 children referred to FNAB between 2006 and 2018, 30 (5.9%) pediatric patients (10 females), mean age 5.7 years (1.2–13.8, median 4.9 years) were diagnosed with IET. A retrospective analysis of medical files of patients diagnosed with IET between 2006 and 2018. Assessed data included ultrasound characterisation, elastographic strain ratio (SR) results and hormonal evaluation. Analysis of thyroid US scans revealed that the mean age at the first thyroid ultrasound was 5.7 (1.2–13.8, median 4.9) years, and at the last US 10.7 (3.7–18, median 10.5) years. The mean time of the IET observation was 59.6 (2–148, median 53.5) months. On US, IET was hypoechoic with multiple linear and punctate echoes, hypovascular, fusiform on longitudinal plane and round or polygonal on an axial plane, more common in the right thyroid lobe (66.7%) and located in the posterior part of the lobes (54.5%), bilateral in two patients and multifocal in one patient. SR of IET was similar to the surrounding normal thyroid tissue. Complete regression of IET was observed in 12/30 patients after a mean time of 81.7 months (median 76.5), at the mean age of 13.7 (9.2–18, median 13.9) years. FNAB was performed in 10/30 and a hemithyroidectomy in 1/30 IET patients. In the FNAB (+) group, patients were younger (5.08 vs 6.08 years) and lesions were larger (0.12 ml vs 0.05 ml) than in the FNAB (−) group. All patients with IET were euthyroid with negative TPOAb and TgAb levels. The reproducibility of unique ultrasound features of IETs allows for safe long-term follow-up of these benign lesions in the majority of pediatric patients: not only monitoring the regression of IET but also screening towards the rare occurrence of a tumor arising from the IET.

Thymic masses are one of the most common tumors in the anterior mediastinum. Nevertheless, because the thymus originates in the third and fourth pharyngeal pouches and descends into the anterior mediastinum, ectopic thymic tissue may be found anywhere from the angle of the mandible to the superior mediastinum. Ectopic cervical thymoma (ECT) is an extremely rare tumor that originates from ectopic thymic tissue trapped during the migration of the embryonic thymus and is often misdiagnosed as a thyroid tumor or other neck masses. Herein, we report an unusual case of ectopic cervical thymoma associated to myasthenia gravis (MG).

Patient: Male, 49-year-old Final Diagnosis: Thyroid carcinoma showing thymus-like differentiation (CASTLE) Symptoms: Hoarseness Medication: — Clinical Procedure: Thyroidectomy Specialty: Surgery Objective: Rare disease Background: Thyroid carcinoma showing thymus-like differentiation (CASTLE) is a rare disease entity. It arises from ectopic thymic tissue in the thyroid gland. Patients usually present with enlarging neck mass and hoarseness. Case Report: A 49-year-old man presented to our clinic with hoarseness and a right thyroid mass. Ultrasound showed a 6-cm right thyroid tumor and computer tomography confirmed invasion into the trachea. He received total thyroidectomy together with excision of one-third of the tracheal wall. No gross tumor was left behind. The tracheal defect was repaired using a pedicled right sternocleidomastoid muscle flap. He had a good recovery and was discharged 2 days after surgery. Histology revealed carcinoma showing thymus-like differentiation (CASTLE). The patient had regular follow-up and showed no clinical evidence of recurrence 18 months after surgery. Conclusions: Thyroid carcinoma showing thymus-like differentiation (CASTLE) is a rare yet potentially extensive disease with favorable prognosis. Imaging, such as computed tomography (CT) and magnetic resonance imaging (MRI), is helpful in aiding diagnosis and operative planning. Surgical resection is currently the treatment of choice, with generally favorable outcomes. The role of adjuvant therapies such as radiotherapy and chemotherapy require further studies.

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.

Ectopy of the thymus is a rare anomaly arising during fetal development, where the thymus does not make a complete decent into the thoracic cavity where it should involute in adolescence. The most common complications of an ectopic thymus include tracheal or esophageal compression presenting in childhood. This is a report of a single case of ectopic cervical thymus identified in a 2-month-old infant presenting with Horner's syndrome. Thymic ectopy should be on the differential when performing a radiologic evaluation of a neck mass when imaging characteristics are similar to thymic tissue. Keywords: Horner's syndrome, Ectopic, Thymus, Pediatrics

AimsIntrathyroidal ectopic thymus (ITET) is a rare cause of paediatric thyroid nodules. Although ultrasonography of ITET demonstrates a characteristic appearance similar to that of normal thymus, accurate differentiation from other thyroid nodule etiologies by ultrasonography is difficult, and so that fine needle aspiration (FNA) is usually performed for further analysis. The aim of this study was to evaluate the utility of flow cytometry (FCM) in confirming the diagnosis of ITET in thyroid FNA samples.MethodsFive cases of ITET were retrieved from our thyroid FNA database within a 3-year period. Their clinical information, ultrasonographic features, cytology and FCM findings were retrospectively reviewed. The FCM results were compared with those of 22 T-cell acute lymphoblastic leukaemia/lymphoblastic lymphoma (T-ALL/LBL) cases.ResultsThe FNA smears of all five ITET cases demonstrated abundant lymphocytes of variable sizes, which included some immature lymphoid cells. No Hassall’s bodies or atypical epithelioid cells were recognised. By multicolour FCM analysis including antibodies against CD1a, CD2, CD3, CD4, CD5, CD7, CD8, CD10, CD34, TDT and TCR, all ITET cases showed antigen expression patterns consistent with normal thymocyte maturation. All T-ALL/LBL cases exhibited significant immunophenotypic aberrancy.ConclusionsThe diagnosis of ITET based on FNA cytology is often inconclusive. The presence of immature lymphocytes often raises the concern for LBL. FCM with adequate antigen coverage can reliably distinguish ITET from T-ALL/LBL and make the diagnosis of ITET in FNA samples. Avoiding unnecessary further invasive procedures, providing reassurance to clinician and patient, the accurate diagnosis of ITET by FCM in FNA samples is clinically important.

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.

The appearance of the paediatric thymus changes as the normal process of thymic involution occurs. Thymic tissue may be orthotopic within the anterior mediastinum or ectopically located along the course of its embryological development. The variable appearance of orthotopic and ectopic thymic tissue in children on imaging studies may lead to misinterpretation of the normal thymus as pathology. Recognition of normal thymic tissue can mitigate unnecessary further diagnostic testing and patient anxiety. In this review, we discuss the embryological development and anatomical variants of normal thymus, and demonstrate the multimodality imaging features of the normal thymus in children, including positron-emission tomography, and diffusion-weighted imaging and in- and opposed-phase imaging on magnetic resonance imaging. We demonstrate the normal thymus mimicking pathological processes and discuss features that distinguish normal thymus, including thymic rebound hyperplasia, from pathology.

The intrathyroidal thymic carcinoma is a rare neoplasm. The probable origin of this neoplasm is the presence of ectopic thymic tissue or remnants of the third and fourth branchial arch. The case of a 49-year-old female with an initial diagnosis of medullary thyroid cancer is presented. When she was operated for regional recurrence, 16 years later, the pathology report demonstrates the presence of a intrathyroidal thymic carcinoma. Intrathyroidal thymic carcinoma is considered an independent type of thyroid carcinoma because this entity has specific clinical-pathological characteristics similar to thymic carcinomas and different prognosis than known thyroid carcinomas. We present the case of a patient initially treated as having a medullary thyroid carcinoma who, upon presenting recurrence, the presence of intrathyroidal thymic carcinoma was demonstrated.

Microscopic thymic rests are not uncommon in the lateral neck and upper mediastinum, especially in the pediatric population. The undescended thymus is almost always asymptomatic; however, it may give rise to ectopic thymic tumors. Thyroid and intrathoracic thymic tumors mirror the morphology of their orthotopic counterparts but a diagnosis of ectopic thymic tumor is always challenging owing to extreme rarity and unusual location. This chapter provides an illustrative overview of the benign and malignant ectopic thymic tumors with a special focus on the intrathyroidal location.

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. 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).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. 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.

El timo ectópico intratiroideo (TEI) es una condición benigna poco frecuente, causada por la migración aberrante del timo durante la embriogénesis. Por lo general, se diagnostica incidentalmente como un nódulo tiroideo.Objetivo: Reportar la localización intratiroidea del tejido tímico ectópico y describir los hallazgos ecográficos en niños.Pacientes y Método: Revisamos retrospectivamente los datos clínicos y ecografías de tiroides realizadas en niños con nódulo tiroideo desde enero de 2010 a agosto de 2017 en un hospital nacional pediátrico de tercer nivel. Fueron considerados timos intratiroideos las lesiones intratiroideas hipoecogénicas sólidas con múltiples tractos lineales o puntiformes hiperecogénicos que no modificaron sus características en el seguimiento. El seguimiento ecográfico fue realizado cada 4 - 6 meses. Se analizaron las características ecográficas de las lesiones (localización, lateralidad, tamaño y forma), la indicación de la ecografía y el tiempo de seguimiento.Resultados: De un total de 147 pacientes con nódulos tiroideos, identificamos 12 niños con lesiones sugestivas de TEI (8,1%). Edad media al diagnóstico: 3,9 años (rango 0-8). En todos los casos fue un hallazgo incidental. Las imágenes fueron unilaterales en ocho y bilaterales en cuatro pacientes. Todas las lesiones se ubicaron en la porción media y/o posterior de la glándula. Se adoptó una conducta expectante con seguimiento ecográfico (media 2,2 años; rango 0,83-4), excepto en un niño de 7 años con hallazgos inciertos, que fue operado, confirmándose TEI en el estudio anatomopatológico.Conclusiones: Las inclusiones tímicas intratiroideas son un hallazgo raro pero cada vez más frecuente, posiblemente relacionado con el mayor uso de la ultrasonografía. Los pediatras y especialistas en imágenes deben conocer esta entidad para diferenciarla de otras lesiones tiroideas, evitando estudios diagnósticos y/o tratamientos innecesarios en estos pacientes.

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.

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.

Difficult intubation in neonates has innumerable aetiologies. It especially poses a formidable challenge to save a newborn baby immediately after birth where antenatal details are unavailable. A late preterm neonate was born limp and apnoeic. Several attempts to intubate the baby were unsuccessful. Possibility of subglottic obstruction was considered. The baby died of severe perinatal asphyxia. Autopsy showed a mass around the airway which turned out to be ectopic thymus on histopathology. Ectopic thymus can present as periglottic mass without externally visible cervical swelling and can cause difficult intubation which may lead to serious adverse outcome including death if not anticipated early and managed accordingly.

Thymectomy is part of a multimodal treatment strategy for juvenile myasthenia gravis. Symptoms that persist following thymectomy may be due to residual or ectopic thymic tissue. We report the use of FDG PET/CT to locate residual thymic tissue following thymectomy in a 10 year old girl with acetylcholine-receptor-antibody-positive myasthenia gravis, who remained refractory to medical therapy. The patient subsequently underwent completion thymectomy with improvement but not remission of her condition.

Erol OB, Sahin D, Bayramoglu Z, Yilmaz R, Akpinar YE, Unal OF, Yekeler E. Ectopic intrathyroidal thymus in children: Prevalence, imaging findings and evolution. Turk J Pediatr 2017; 59: 387-394. The aim of this study was to evaluate the ultrasound (US) features of intrathyroidal ectopic thymus (IET) and demonstrate the alterations after follow-up. This study included 36 lesions of 32 patients (mean age 95 ± 58 months) diagnosed with IET. The patients underwent follow-up US examination at least 22-months without a medication or surgical intervention. A total of 36 IETs with an incidence of 0.91% were detected among 3914 thyroid ultrasound (US) examinations. The mean of anteroposterior (ap), transverse (tr), and craniocaudal (cc) diameters in the initial US examinations were 3.1±1.19 mm, 4.89±1.86 mm, and 6.45±3.92 mm respectively. All of the lesions were well-demarcated, hypoechoic to the thyroid gland, and contained uniformly distributed punctate echogenic foci. Follow-up US examinations were performed after 684±85 days. The alterations between the initial and follow-up diameters for ap and cc direction were not statistically significant. However, a significant difference (p=0.007) was found for transverse diameters and the IETs were found to be smaller at follow-up US than in the initial US. Most of the IETs were located in the left lobe (64%), middle portion (83%), and extended to a border of thyroid gland (69%) and nonspherical in shape (89%). The descriptive findings of IETs are uniform distribution of punctate echogenic foci, absence of a rim, and the presence of vessels traversing through the lesion without parenchymal displacement. Given our findings, healthcare professionals should be aware of the diagnosis of IET. Patients with an IET could be safely managed with follow-up US and any surgical treatment would not be required.

As ultrasound is commonly used these days, more and more lesions are found incidentally, including simple cysts, isoechoic nodules, and hypoechoic nodules, such as ectopic thymus. We here report the prevalence of ectopic thymus and its natural course. We retrospectively reviewed the charts of 690 subjects (342 males, 348 females) who were under 18 years old and had undergone neck or thyroid ultrasound at Hallym University Sacred Heart Hospital from January 2014 to June 2017. Ectopic thymus was defined when the incidental lesion was hypo- to iso-echoic compared to adjacent muscles with vascularity and did not have a connection to the thymus in the mediastinum. Of the 690 children, 16 (9 males, 7 females; median and ranges of age at diagnosis, 13 months and 18 days to 10 years) were diagnosed as having ectopic thymus. The most common location of ectopic thymus was in the inferior aspect of the left thyroid lobe. The median and ranges of the longest diameter at the time of initial diagnosis was 22.5 mm and 8 mm to 38 mm, respectively. Four cases underwent follow-up ultrasound, of which 3 cases showed no change in size and 1 case showed decreased size. Ectopic thymus should be kept in mind when a lesion is found in the neck and thyroid incidentally, and physicians should reassure parents about its benign course.

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.

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.

Background: Carcinoma showing thymus-like differentiation (CASTLE) is an extremely rare malignant neoplasm of the thyroid that originates from ectopic thymic tissue. No sufficient evidence exists regarding the efficacy of chemotherapy for cases with distant metastases or advanced disease because of the rarity of the disease itself. Patient: We report a case of CASTLE with lung metastasis that showed good responses to first-line (cisplatin, doxorubicin, vincristine, and cyclophosphamide) and second-line (carboplatin and paclitaxel) chemotherapies. Summary: This is the first case of CASTLE reported to show a good response to two serial chemotherapies. Conclusion: This case suggests that CASTLE is a chemosensitive tumor and that chemotherapy should be attempted in patients with advanced or metastatic CASTLE.

We report herein on a case of ectopic cervical thymus in a 5-year-old boy and the literature is reviewed. Swelling of the right neck was seen in the patient in his newborn period and it was diagnosed as cystic disease of the neck in a previous hospital at 4 months of age. Ultrasonography (US) and MRI revealed a cervical tumor consisting of a solid component in our hospital, and histopathologic examination showed no evidence of malignancy. The lesion revealed almost no change in size but showed a mosaic pattern on US, whereon the parents agreed to the removal of the tumor. Intraoperatively, the tumor could be easily dissected from the surrounding tissue and resected. The pathological diagnosis was normal thymic tissue. The postoperative course was uneventful and no complication or immunological disorders were seen. A cervical ectopic thymus is a congenital lesion that results from abnormal thymic migration during embryogenesis. Most patients are asymptomatic and the condition is found incidentally. Preoperative diagnosis of cervical ectopic thymus in children is rarely made, so surgical treatment is the definitive means of pathological diagnosis. This disease should be listed in the differential diagnosis for neck masses in children, and should be suspected when the mosaic pattern is detected in the lesion on US.

Present study included 22 participants range in age from 1.5 to 16 years old with ultrasound features of an ectopic thymus in thyroid gland. The lesion structure was typical for the thymus in each case. The location and size of the thymus was normal. The ectopic lesions of thymus in thyroid gland had oval (89.7%) or irregular (10.3%) shape with sharp (100%) and irregular (79.3%) or regular (20.7%) contour, low echogenecity (100%), thin regular linear (100%) in combination with granular hyperechoic (31%) inclusions, avascularity (86.4%) or hypovascularity (13.6%). In 5 lesions larger than 10 mm the diagnosis was confirmed by fine-needle aspiration biopsy. The follow-up period was 9–36 months. In one case (the 7-year old boy) with confirmed diagnosis the lesion had been reduced on 34% during the follow up period of 9 months. There were no changes in other patients during the follow-up. We consider it is reasonable to suggest the ectopic thymus in thyroid gland if these ultrasound features are revealed. The lesions of ectopy more than 10 mm require the morphological confirmation. The long follow-up of these patients for expected regression or potential transformation is necessary.

Purpose To assess the prevalence of ectopic thyroidal thymus tissue detected by sonography (US) in children and to analyze the US features. Methods We retrospectively reviewed images of 216 children who had undergone a thyroid or neck US examination from February 2015 to June 2015. Lesions within or adjacent to the thyroid gland that showed echopatterns consistent with thymic tissue were diagnosed as ectopic thyroidal thymus tissue. Lesions were reviewed according to their side, location, level, size, shape, echo pattern, internal content, and vascularization. Results A total of 216 children (119 girls, 97 boys) with a mean ± SD age of 8.6 ± 5.2 years were enrolled the study.Thirty children (13girls, 17 boys) (13.9%) had 35 lesions compatible with ectopic thyroidal thymus tissue.Nine children had intrathyroidal (4.2%) and 21 children had extrathyroidal (9.7%) ectopic thymus tissue.The mean ± SD ages of the children with and without ectopic thyroidal thymus tissue were 6.0 ± 3.6 years and 9.1 ± 5.2 years, respectively (P = .002). Twenty-five of the lesions were extrathyroidal and 10 were intrathyroidal. All extrathyroidal and most (8/9) intrathyroidal ectopic thymuses had fusiform shape with well demarcated contours. Ectopic thymuses were located either in the midportion (n = 23) or lower portion of the neck (n = 12). Both extrathyroidal and intrathyroidal ectopic thymuses showed typical hypoechoic (n = 22/25, n = 9/10, respectively) or hyperechoic (n = 3/25, n = 1/10, respectively) echo patterns with internal linear and punctate echoes. Conclusions Ectopic thyroidal thymic tissue is common in children. Radiologists should be vigilant about the unique US features of ectopic thyroidal thymus, including a hypo- and hyper-echoic echo pattern with multiple linear and punctate echoes, a fusiform shape, well-demarcated contours, and middle or low-lying location to differentiate it from other neck or thyroid lesions.

Aims: Intrathyroidal ectopic thymus (IET) is being increasingly reported in the radiology literature. Most of the reports are of individual cases or small series and prevalence and natural course of the pathology is not well known. The purpose of this study is to establish the prevalence of IET in children and report long term follow-up results.Material and methods: In 180 children who were examined by ultrasound (US) for other reasons, 7 patients were indentified with IET. Together with the other seven children who were already under follow-up for IET (diagnosed using US criteria), these 14 patients were followed up with US for 30 months. Size, shape, location, echotexture and internal echoes of the lesions were evaluated.Results: There were 16 lesions in 14 children. The most common appearance was a fusiform hypoechoic lesion, with punctate and linear internal echoes and well-defined but slightly irregular borders located posteriorly in the lower thirds of the thyroid. In follow-up, there were no changes in echotexture, shape or border. In 3 patients, the lesion became slightly smaller, in a 10-year-old boy slightly larger, and in an 11-year old boy the lesion disappeared. In a patient with bilateral lesions, one lesion slightly decreased in size.Conclusions: IET in children may be more common than thought. Its growth reflects that of a normal thymus. Awareness of this entity is important in order not to misdiagnose them, especially as papillary cancer, and to prevent unnecessary interventions.

Recent research has emphasized the capacity of thymus cells of producing parathyroid hormone (PTH) if adequately stimulated, and have investigated the role of the so-called “thymic PTH”, produced by the medullary thymic epithelial cells (m-TECs). To the best of our knowledge, only a single case of well-documented PTH secretion from a thymoma causing primary hyperparathyroidism (PHTP) has been reported in the literature so far. We report here the case of a female patient with PHTP who underwent neck exploration for a suspected parathyroid adenoma. After surgery, a normalization of serum PTH concentration was observed, but the histological examination of the surgically excised mass revealed exclusively normal thymus tissue. The present case provides additional evidence of PHTP caused by an ectopic thymus.

Ectopic thymic tissue in neck is not uncommon; however, ectopic thymic cysts in neck are rare and intrathyroidal thymic cyst is still rarer. Multilocular proliferating thymic cyst is a rare entity and very few cases are described in mediastinum. We present the first case of a 73-year-old male with an intrathyroidal multilocular proliferating thymic cyst mimicking thyroid malignancy radiologically.

We present an unusual case of a lateral neck mass presenting in conjunction with a thyroglossal duct cyst with review of literature. A 7-year-old boy presented with a midline mass consistent with a thyroglossal duct cyst and a second lesion adjacent to the left inferior lobe of the thyroid confirmed to be ectopic thymus after excision. This is the first reported case of ectopic cervical thymus diagnosed in conjunction with a thyroglossal duct cyst. It is possible that both lesions developed by a similar mechanism. The treatment of choice for both masses is surgical excision.

Carcinoma showing thymus-like differentiation (CASTLE) is a rare intrathyroidal neoplasm, probably arising from ectopic thymus or branchial pouch remnants. The tumor was first reported by Miyauchi et al. [1].The clinical and pathological features of this tumor were classified by Chan et al. [2] into 4 groups: ectopic hamartomatous thymoma, ectopic cervical thymoma, spindle ephithelial tumor with thymic-like differentiation (SETTLE), and carcinoma showing thymus-like differentiation (CASTLE). Recently, CASTLE has been designated as an independent clinicopathologic entity of thyroid tumors in the most recent edition of the World Health Organization classification of tumors of endocrine organs[3].To our knowledge, less than 100 cases of CASTLE have been reported in the literature, 45 cases of which (including one of the authors' patient) have been identified in China. We report a new case of this entity and suggest recommendations for diagnosis.

A 16-day-old baby presented noisy breathing, stridor at feeding, dyspnea and desaturations. MRI examination showed the presence of a left retro-parapharyngeal mass that surrounded the carotid artery and jugular vein. From ultrasonography, a tentative diagnosis of normal thymic tissue was obtained. An endoscopic excision of the retropharyngeal component successfully relieved the airway obstruction. Microscopic examination confirmed the diagnosis of normal ectopic thymus. Three months after surgery, no evolution in size or vascular compression was found on a post operative MRI of the residual parapharyngeal tissue. Ultrasonography proved to be very useful in the management of this rare solid lesion.

Objective The role of extended thymectomy in the treatment of class I myasthenia gravis is still controversial. This study compared the long-term outcomes of operated and nonoperated patients allocated according to their will. Methods We retrospectively reviewed 47 patients with class I nonthymomatous myasthenia gravis undergoing extended thymectomy between 1980 and 2007. These patients were matched with 62 class I patients who refused surgery and received only pharmacologic therapy. Outcomes were stable remission and clinical or pharmacologic improvement. Predictors of remission were analyzed by Kaplan–Meier and Cox regression. Results We observed low postoperative major morbidity (n = 2; 4.2%) and no perioperative mortality. Heterotopic thymus was found in 22 patients (46%). Twenty-one patients showed active germinal centers, in the heterotopic thymus in 12 patients (57.1%). Thirty operated patients (64%) versus 34 nonoperated patients (55%) achieved stable remission, and 8 patients (17%) versus 5 patients (9%) showed pharmacologic improvement. Nine patients who had no postoperative improvement showed active ectopic thymus. Surgery was a marginal prognosticator ( P = .053). Early treatment (≤6 months from symptoms onset) was the unique significant prognosticator ( P = .045), but this was due to the contribution of the operated patients ( P = .002). Other predictors of remission in the operated group were the absence of ectopic thymus ( P = .007) with no germinal centers ( P = .009). No significant predictor of remission was found in the nonoperated group. Conclusions Extended thymectomy achieved a more rapid remission than after nonsurgical treatment of class I myasthenia gravis. Significantly better outcomes resulted when thymectomy was performed within 6 months from the onset of symptoms.

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare tumor usually localized in the thyroid gland and perithyroid tissues. It is considered to arise from ectopic thymic tissue or branchial pouch remnants. It occurs more frequently in children and adolescents. We report 2 cases of spindle epithelial tumor with thymus-like differentiation localized in the thyroid gland, and 1 of them was associated with a parathyroid adenoma. We emphasize the need for a close and long-term follow-up in these patients.

Carcinoma showing thymus-like elements (CASTLE) is a rare malignant neoplasm of the thyroid gland, morphologically and immunohistologically similar to a thymic carcinoma, whose histogenesis is still debated. Hypotheses include an origin from ectopic thymic tissue, vestige of the thymopharyngeal duct, or branchial pouch remnants from which solid cell nests (SC-nests) originate. The diagnosis of CASTLE may be treacherous due to its rarity and its propensity to mimic other poorly differentiated tumors such as squamous cell carcinoma.We present a case of CASTLE in a 58-year-old man initially diagnosed as a poorly differentiated squamous cell carcinoma both on fine-needle aspiration cytology (FNAC) and on biopsy, arising in close association with SC-nests. A thorough literature review, with special emphasis on its diagnosis and histogenesis of CASTLE, was also conducted.Magnetic resonance images revealed a 4.0-cm cervical mass on the left side of the trachea, involving the lateral middle/inferior portion of the left lobe of the thyroid gland. FNAC was performed with a diagnosis of "malignant cells, consistent with squamous cell carcinoma." A histological evaluation of the resected specimen revealed a malignant proliferation of cells, focally exhibiting a squamoid appearance, which were immunopositive for CD5 and p63. A diagnosis of CASTLE was made. The tumor was located in direct continuity with SC-Nests, and the cell morphology of both the SC-nests and CASTLE was very similar with merging. Moreover, the immunohistochemical expression profiles of most markers useful in the diagnosis of CASTLE were identical in the SC-nests.The inclusion of CASTLE in the differential diagnosis of poorly differentiated tumors of the thyroid region and the use of ancillary studies are essential to diagnose this rare entity associated with a relatively favorable prognosis. The close association of CASTLE with SC-nests opens the way to a new scenario for studies of its histogenesis.

The purpose of our article is to describe the immunohistochemical findings of intrathyroidal epithelial thymoma/carcinoma showing thymus-like differentiation (ITET/CASTLE) of the thyroid in detail, to clarify the difference between ITET/CASTLE and thymic lymphoepithelioma-like carcinoma (LELC), and to discuss the pathogenesis of ITET/CASTLE. We immunohistochemically examined five ITET/CASTLE and eight LELC cases. All of ITET/CASTLE cases were strongly positive for CD5, P63, high-molecular-weight cytokeratin and B-cell CLL/lymphoma-2. Carcinoembryonic antigen-positive carcinoma cells were found in four ITET/CASTLE cases. Neuroendocrine marker-positive carcinoma cells were scattered in all cases. Immunohistochemical findings in thymic LELC were essentially similar to those in ITET/CASTLE, but the sensitivity was different. There is a possibility that ITET/CASTLE and thymic LELC are not the quite same disease entity. We think that ITET/CASTLE is derived from ectopic thymus, but not related to solid cell nests.