CT and MR imaging of thyroid carcinoma showing thymus-like differentiation (CASTLE): a report of ten cases

Carcinoma Showing Thymus-like Differentiation (CASTLE) with Synchronous Papillary Thyroid Carcinoma: A Case Report and Review

Carcinoma showing thymus-like differentiation (CASTLE) is a rare malignant tumor that accounts for 0.1%-0.15% of all thyroid cancers. More than half of the patients have tumor extension to adjacent organs, including the recurrent laryngeal nerve, trachea, and esophagus. The diagnosis of CASTLE is based on histology and immunohistochemistry. A 58-year-old female patient complained of hoarseness for one and half years. Right side vocal cord palsy was diagnosed by fiberscopy. Thyroid sonography revealed right thyroid tumors, which were reported to be papillary thyroid carcinoma through FNAC. Total thyroidectomy with central lymph node dissection was performed. Pathologist found 2 isolated malignancy tumors. One patient in the right thyroid lobe had papillary thyroid carcinoma features. The other extrathyroid tumor seemed to be separated from the first tumor and invaded the thyroid capsule. After multiple immunohistochemical studies, PTC synchronous CASTLE was the final diagnosis. Coexisting PTC and CASTLE is very rare. This is the first report to describe a case showing PTC at first, while subsequent pathologic examination revealed the presence of CASTLE in addition to PTC. Since the prognosis of CASTLE is favorable, the treatment is different from other aggressive thyroid cancers, such as poorly differentiated or anaplastic thyroid carcinoma.

Coexistence of intrathyroid thymic carcinoma and papillary thyroid carcinoma: a case report and literature review

Background

Intrathyroid thymic carcinoma (ITTC) is a rare neoplasm of the thyroid, which accounts for less than 0.15% of all thyroid malignancies. The coexistence of ITTC and papillary thyroid carcinoma (PTC) is an extremely rare condition reported only in a limited number of cases.

Case summary

A 26-year-old female presented with a growing neck mass, hoarseness, and dysphagia over four months. Ultrasonography revealed that the entire left lobe and the isthmus of the thyroid were replaced with a hypoechoic mass. Moreover, it revealed two hypoechoic nodules in the right thyroid. The patient underwent a total thyroidectomy and paratracheal lymph node dissection. Histopathological examinations revealed the coexistence of ITTC and PTC in the same thyroid. In immunohistochemical analyses, the ITTC was positive for CD5, P63, CD117, and CK 5/6 and negative for thyroglobulin, calcitonin, and TTF 1. At the same time, PTC was positive for TTF 1 and thyroglobulin and negative for CD5, P63, and CK 5/6. The patient received postoperative radiotherapy and remained well with no evidence of recurrence during one month follow-up.

Conclusion

Distinguishing ITTC from other thyroid malignancies before the surgery is challenging due to its non-specific presentations. Therefore, the diagnosis relies on postoperative studies, especially immunohistochemistry. The recommended treatment approach to improve survival in ITTC cases is total thyroidectomy combined with cervical lymph node dissection, followed by postoperative radiotherapy. The coexistence of ITTC and PTC may indicate the similarity in the underlying mechanisms of these tumors. However, further investigations are needed to understand this potential correlation.

Case Reports: A role of postoperative radiation therapy in completely resected early stage intrathyroid thymic carcinoma: a case report and literature review of the diagnosis and treatment

Background

Intrathyroid thymic carcinoma (ITTC) is a rare malignant tumor of the thyroid, probably arising from ectopic thymus or branchial pouch remnants. Most of the literature recommended radical resection as the fundamental treatment for ITTC, and postoperative radiation appears to be able to reduce the recurrence rate in patients with advanced ITTC. However, the issue of adjuvant radiotherapy in completely resected early-stage ITTC has been controversial.

Case presentation

Here, we reported a new case of early-stage ITTC that treated with total thyroidectomy and the right central neck dissection. Postoperative external beam radiation therapy (50.0 Gy/25 fractions) was given to the thyroid bed and bilateral cervical lymph node area since the tumor involved part of the sternal thyroid muscle. At 4-year follow-up after completion of radiotherapy, she is without evidence of locally recurrent or distant disease.

Conclusion

Since there are no current guidelines for early-stage ITTC, in combination with this case and previous literature, we may suggest routine adjuvant radiotherapy should be considered in patients with incompletely resected tumors and extraparenchymal extension of ITTC. Moreover, we summarized comprehensive and advanced diagnosis, treatment, prognosis of ITTC and comparison between ITTC, primary squamous cell carcinoma of thyroid gland, differentiated thyroid cancer, and anaplastic thyroid cancer.

Spindle Epithelial Tumor With Thymus-Like Differentiation of Thyroid (SETTLE): A Case Report and Literature Review

Spindle epithelial tumor with thymus-like differentiation of thyroid (SETTLE) is very rare neoplasm with 2 cellular forms, epithelial cell and spindle cell, and most reported cases have been in young people. An 11-year-old boy presented with painless swelling of the right neck lasting for more than 2 months. A tumor size measuring approximately 3 × 3 cm was resected, and intraoperative frozen pathology suggested a spindle cell tumor, which was confirmed as SETTLE by immunohistochemical staining and external hospital consultation. The immunohistochemical staining profile of the resected tumor tissue was as follows: cytokeratin (CK) (+), smooth muscle actin (weak+), vimentin (+), CK7 (focal+), B-cell lymphoma 2 (partial+), CD99 (-), calcitonin (+), galectin-3 (+), CK19 (+), and Ki-67 (10%+). Ultrasound at 1-year postoperative follow-up revealed no local recurrence of the lesion or lymph node metastasis in the thyroid gland. We summarized the disease characteristics of SETTLE among 6 cases reported to date and found that SETTLE is associated with a good prognosis and low postoperative recurrence rate. Thus, for this type of malignant thyroid tumor, diagnosis depends mainly on postoperative pathology and immunohistochemical staining and simple surgical resection is recommended.

Thyroid Carcinoma Showing Thymus-like Differentiation (CASTLE): A Case Report

Background and Objectives: Carcinoma showing thymus-like differentiation (CASTLE) is a low-grade thyroid carcinoma, with an indolent clinical course and usually a favorable prognosis. The clinical and imagistic features are not specific for CASTLE but similar to other malignant lesions of the thyroid. Definite diagnosis is based on an immunohistochemical examination, as this carcinoma shows positive CD5 immunoreactivity when compared to other aggressive thyroid carcinomas. Case presentation: The main focus of this study is to outline a rare case of CASTLE compressing the trachea in a 50-year-old female patient who was initially diagnosed with undifferentiated thyroid carcinoma, for which she underwent unsuccessful surgery, as well as postoperative radiotherapy and chemotherapy. After receiving a second medical opinion, the patient underwent a challenging radical resection consisting in total thyroidectomy and central neck dissection, with no local recurrence after 6 months and 2 years of follow-up and negative metastatic follow-up. The correct diagnosis has been established based on pathological and immunohistochemical examinations. Conclusions: In summary, the diagnosis of CASTLE is difficult and requires an experienced histological analysis and CD5 immunoreactivity. Lack of metastasis, complete removal of the tumor, and a low degree of tumor infiltration into nearby structures are all associated with better long-term survival.

Genomic variation associated with carcinoma showing thymus‐like elements ( CASTLE ) in thyroid gland

Background

Methods

Results

Conclusions

Inoperable CASTLE of the thyroid gland treated with radical radiotherapy with complete remission

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.

Thyroid Carcinoma Showing Thymus-Like Differentiation (CASTLE) with Tracheal Invasion: A Case Report

Patient: Male, 49-year-old

Final Diagnosis: Thyroid carcinoma showing thymus-like differentiation (CASTLE)

Symptoms: Hoarseness

Medication: —

Clinical Procedure: Thyroidectomy

Specialty: Surgery

Management and Prognostic Factors for Thyroid Carcinoma Showing Thymus-Like Elements (CASTLE): A Case Series Study

Introduction: This study aims to identify the prognostic factors that influence therapeutic modalities for thyroid carcinoma showing thymus-like elements (CASTLE).

Materials and Methods: Reported studies with CASTLE patients published between 2004 and 2018 were retrieved from a cross-database literature search. Three patients treated in our institute were also included as one case series. Standardized data collection was performed; data pertaining to clinical stages, treatment regimens, and survival time were collected and statistically analyzed.

Results: Up to 26 case series of CASTLE were selected, including 51 males and 38 females with a median age of 48 years. Follow-up time ranged from 2 to 362 months and the median survival time was 158.03 months. Lymph node metastasis and tumor invasion of adjacent tissue both showed a significant negative effect on survival (p = 0.001 and 0.013, respectively). Radiotherapy significantly improved survival (p = 0.034), while neck dissection significantly prolonged survival only in patients with extrathyroidal extension (p = 0.043).

Conclusions: Extrathyroidal infiltration and nodal metastasis are important factors in cancer outcomes. Radiation therapy appears to be important for better outcomes in CASTLE patients, and neck dissection is recommended for patients with extrathyroidal extension.

Intrathyroid thymic carcinoma: report of two cases with pathologic and immunohistochemical studies

Intrathyroid thymic carcinoma (ITCA) is a rare neoplasm of the thyroid gland, that is difficult to diagnose because of its complex pathologic and immunohistochemical characteristics. Here, we report two cases that may provide a better understanding of this disease. Case 1 is a 30-year-old man, and Case 2 is a 42-year-old man. The two cases showed an irregular solid thyroid mass on sonography. Histological examination revealed the solid growth of epithelial cells separated by bands of dense, hyalinized, and fibrous stroma. Tumor cells were positive for the expression of CD5, HMWK, CK19, CK5/6, CK7, EMA, CD117, p63, Bcl-2, and NANOG. It is noteworthy that the neuroendocrine markers Syn, NSE, and CgA were also observed. In Case 1, chemotherapy combined with radiotherapy, chest CT showed lung metastasis 4 months after resection. The patient was alive as of postoperative follow up lasting 46 months. Radical operation combined with radiotherapy was performed in case 2, and the patient was alive as of follow-up lasting 42 months.

CASTLE tumor of the parotid: First documented case, literature review, and genetic analysis of the cancer

BACKGROUND

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that normally affects the thyroid gland and was thought to arise from either the remnants of the branchial pouch or the ectopic cervical thymic tissue. These tumors show strong immunopositivity for CD5, P63, and CD117. Most CASTLE of the thyroid gland is treated with surgery with or without adjuvant radiotherapy or chemotherapy.

METHOD

A 55-year-old woman presented with a slow-growing right parotid mass. A right total parotidectomy and ipsilateral selective neck dissection were performed and the diagnosis of CASTLE was made after confirmation with an immunohistochemistry test. She received radiotherapy postoperatively.

RESULTS

Genetic sequencing showed alterations in the PPARG, BRCA2, and NOTCH1 genes. She remained disease free for >1 year after treatment.

CONCLUSION

We believe that this is the first reported case of CASTLE in the parotid gland. Clinicians should be aware of this rare entity and consider this differential diagnosis after ruling out other common parotid lesions.

Carcinoma showing thymus like elements: Report of a case with EGFR T790M mutation

Carcinoma showing thymus-like differentiation of the thyroid (CASTLE) is a rare tumor involving the thyroid and perithyroidal soft tissues. It shares morphological, immunohistochemical and molecular similarities with thymic carcinomas. Due to its relatively better prognosis, it needs differentiation from other primary and metastatic tumors of this region. A 40-year-old lady presented with a gradually progressive anterior neck swelling for one year. Imaging showed bulky right and left lobes of thyroid along with a solid soft tissue mass in the pretracheal region. Fine needle aspiration smears showed features of poorly differentiated carcinoma. Total thyroidectomy with excision of the mass revealed histopathological features characteristic of CASTLE, with evidence of thyroiditis in adjoining thyroid. Epidermal growth factor receptor (EGFR) assay revealed presence of EGFR T790M somatic mutation in exon 20. The same was not detectable on direct sequencing. We present a rare case of CASTLE, occurring in association with Hashimoto thyroiditis, with emphasis on cytological features and report for the first time the presence of a low level somatic mutation in EGFR (EGFR T790M mutation).

An analysis of clinical characteristics and patient outcomes in primary mediastinal sarcomas

BACKGROUND

Published data concerning primary mediastinal sarcomas are limited to small-sized retrospective series.  This study reviewed the clinical outcomes of these cases from the SEER (surveillance, epidemiology and end results) database.

METHODS

Primary mediastinal sarcomas (1988 - 2013) were assembled from the SEER database. The incidence and 10-year cancer-specific survival rates were compared to other primary mediastinal malignancies (thymic carcinoma, germ cell tumors, neurogenic tumors, Hodgkin / non Hodgkin lymphomas) as well as to non mediastinal sarcomas.

RESULTS

A total of 204 patients were recruited into this cohort. Multivariate analysis showed better overall survival for patients with younger age at diagnosis, low grade [hazard ratio 0.427 (95% CI: 0.224-0.814; P= 0.010)], posterior mediastinum location [hazard ratio 0.458 (95% CI: 0.268-0.781; P= 0.004)], node negative disease [hazard ratio 0.463 (95% CI: 0.232-0.923; P= 0.029)] and surgical treatment [hazard ratio 0.488 (95% CI: 0.336-0.709; P <0.0001)]. Compared to other mediastinal malignancies, primary mediastinal sarcomas have the worst 10-year overall survival. Similarly compared to non mediastinal sarcomas, primary mediastinal sarcomas have worse 10-year overall survival (23% versus 55%).

CONCLUSION

Primary mediastinal sarcoma is a rare entity with worse prognosis compared to non-mediastinal counterparts. Surgical resection plays a particularly important role in the management.