Thyroid carcinoma showing thymus-like differentiation (CASTLE): case report with cytomorphology and review of the literature

Failure pattern and suggestions for target volume delineation of carcinoma showing thymus-like differentiation treated with intensity-modulated radiotherapy

BACKGROUND

To review our long-term clinical experience, analyze the failure patterns, and give suggestions for target volume delineation of carcinoma showing thymus-like differentiation (CASTLE) treated with intensity-modulated radiotherapy (IMRT).

METHODS

From April 2008 to May 2019, 30 patients with CASTLE treated by postoperative or radical IMRT in our center were retrospectively reviewed. A total dose of 56-60 Gy in 28-30 fractions was prescribed to patients without residual disease and 66 Gy in 33 fractions for patients with residual or unresectable disease. Survival rates were calculated using the Kaplan-Meier method. Treatment-related toxicities were graded by National Cancer Institute Common Toxicity Criteria (NCI-CTC) version 4.0.

RESULTS

Among the 30 patients, 12 (40%) received partial resection or biopsy. Lateral lymph node metastasis was observed in 7 (23.3%) patients. During follow-up, regional lymph node recurrence occurred in 2 patients and distant metastasis in 5 patients. With a median follow-up time of 63.5 months, the 5-year local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), distant metastasis-free survival (DMFS), overall survival (OS) and progression-free survival (PFS) rates were 100, 88.9, 78.9, 93.1 and 78.9%, respectively. For patients with no lateral neck node metastasis, prophylactic radiotherapy for lateral neck nodal regions failed to improve RRFS (p = 0.381) and OS (p = 0.153).

CONCLUSION

Distant metastasis was the major failure pattern for CASTLE after surgery and IMRT. For patients with no lateral neck node metastasis, the omission of irradiation for lateral neck nodal regions seems to be safe and feasible.

A case of concurrent occurrence of carcinoma showing thymus-like differentiation and follicular variant of papillary thyroid cancer in the same thyroid

Carcinoma showing thymus-like differentiation (CASTLE) is a rare thyroid cancer. This is the first report of a case of concurrent occurrence of CASTLE with papillary thyroid carcinoma (PTC).

A 66-year-old male patient had hoarseness with right vocal cord paralysis. Ultrasonography revealed a hypoechoic nodule in the inferior pole of the right thyroid lobe. Ultrasound-guided fine-needle aspiration cytology suggested differentiated thyroid cancer. The patient underwent total thyroidectomy with neck dissection. Pathological examination revealed two different thyroid cancers: a CASTLE and a follicular variant of PTC. Postoperative radiation therapy was performed. The patient was still alive after 5 year following the initial treatment without evidence of recurrence. The oncological management of patients with concurrent occurrence of different thyroid cancers should consider the biological behavior of both tumors.

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

Pembrolizumab in a Patient With a Metastatic CASTLE Tumor of the Parotid

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor, most commonly found in the thyroid gland. Here we report a case of CASTLE tumor localized to the parotid gland, recognized in retrospect after a late manifestation of symptomatic pleural carcinomatosis. The original tumor in the parotid gland was treated by surgery followed by radiotherapy. Ten years later, a metastatic disease with recurrent pleural effusions occurred. Pleural carcinomatosis was strongly positive for CD5, CD117, and p63 as was the original tumor of the parotid, which allowed the diagnosis of a CASTLE tumor. Additionally, the pleural tumor expressed high levels of programmed death ligand 1 (PD-L1), and the patient underwent treatment with the monoclonal PD-L1 inhibitor pembrolizumab achieving a partial remission. To the best of our knowledge, this is the first patient with a metastatic CASTLE tumor treated with a PD-L1 inhibitor.

Intrathyroidal thymic carcinoma exhibiting neuroendocrine differentiation: Case report with cytomorphology, immunocytochemistry, and review of the literature focusing on cytology

Intrathyroidal thymic carcinoma is a malignant epithelial tumor of the thyroid gland with thymic epithelial differentiation; it is the malignant counterpart of ectopic thymoma of the thyroid gland and histologically resembles thymic carcinoma. Given its favorable prognostic course, preoperative cytological diagnosis is important to distinguish this neoplasm from other more aggressive thyroid neoplasms that can have similar or overlapping cytomorphological features. However, there is little information about the cytology of this disease available in the literature, even in the latest fourth edition of World Health Organization classification of tumors of endocrine organs. Here, we report a case of intrathyroidal thymic carcinoma exhibiting neuroendocrine differentiation in a 33-year-old woman and present a review of the literature.

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.

Clinical outcome of intensity modulated radiotherapy for carcinoma showing thymus-like differentiation

PURPOSE

To evaluate the efficacy and toxicity of adjuvant intensity-modulated radiotherapy (IMRT) after surgery for carcinoma showing thymus-like differentiation (CASTLE).

METHODS

Between September 2008 and June 2015, 14 CASTLE patients were retrospectively enrolled. The clinical features, treatment procedure and clinical outcomes were reviewed. All patients received postoperative IMRT. The radiation doses ranged from 56Gy/28 fractions to 66Gy/33 fractions. Treatment-related toxicities were graded by National Cancer Institute Common Toxicity Criteria (NCI-CTC) version 3.0.

RESULTS

After a median follow-up period of 42 months, only one patient suffered local recurrence and distant metastasis. The most frequently seen acute toxicities were mucositis and dermatitis (grade 1-2). No grade 3-4 toxicities were observed.

CONCLUSIONS

Although based upon a small series of consecutively treated patients, our study showed that adjuvant IMRT provides satisfactory local-regional control for CASTLE, with acceptable toxicities. Further studies are still warranted to clarify our findings.

CASTLE Thyroid Tumor: A Case Report and Literature Review

Carcinoma showing thymus-like differentiation is a rare tumor of the thyroid gland, which is structurally similar to thymic tissue. Overall, it has a favorable prognosis. Radiotherapy has been shown to be an effective local treatment, but there have been reports of distant recurrence. It has been suggested that adding chemotherapy may decrease the risk of recurrence. Here, we present a case report of a patient with a large tumor and extrathyroidal extension. The patient was treated with surgery, radiotherapy, and cisplatin with acceptable toxicity. The patient is free of locally recurrent or distant disease at 3 years.

Carcinoma Showing Thymus-Like Differentiation (CASTLE): Cytopathological Features and Differential Diagnosis

BACKGROUND

CASTLE (carcinoma showing thymus-like differentiation) is a rare tumor (accounting for less than 0.15% of thyroid neoplasms) with most of the reported cases from Asia. Although this tumor is rare, distinguishing it from more aggressive neoplasms is critical because of its improved prognosis. To date, there have been limited studies on its cytomorphological features. Herein, we review the cytomorphological features of 10 fine-needle aspiration (FNA) cases of histologically confirmed CASTLE and discuss the findings in light of the current literature.

METHODS

We retrospectively (1989-2016) identified 10 cases of CASTLE from 17,415 surgical cases of thyroid carcinoma from The Johns Hopkins Hospital and Fudan University Shanghai Cancer Center. The cases were reviewed for discrete cytomorphological characteristics.

RESULTS

All of the cases displayed predominantly single (dishesive) epithelial cell populations, high nuclear/cytoplasmic ratios, hyperchromatic to open/vesicular nuclei and macronucleoli. The majority of cases additionally showed hypercellular, three-dimensional fragments in a background of lymphocytes. The fragments displayed syncytial architecture without molding and rarely squamous differentiation. All cases lacked follicular differentiation, intranuclear inclusions, nuclear molding, or neuroendocrine-type chromatin.

CONCLUSIONS

Cytopathological features alone do not appear to be distinctive or definitive of CASTLE but rather allow for the inclusion of CASTLE within the differential diagnosis. Procurement of cell block material is important and resulted in the single case of CASTLE accurately diagnosed on FNA. Cytopathological features that favored CASTLE included syncytial fragments of malignant cells with pleomorphic large nuclei, vesicular chromatin, and prominent nucleoli in a background of lymphocytes. These cytopathological findings in the appropriate clinicoradiological context warrant its inclusion in the reported differential diagnosis in order to be able to implement appropriate clinical management.

Carcinoma showing thymus-like elements of the thyroid gland: report of three cases including one case with breast cancer history

Carcinoma showing thymus-like elements (CASTLE) is a rare malignant tumor of the thyroid or adjacent neck soft tissues, whose histogenesis is still debated. It may resemble other primary or metastatic poorly differentiated tumors histologically and the differential diagnosis is crucial for CASTLE has a better prognosis. However, CASTLE as a second primary tumor has not been reported in the literature. We report three cases of thyroid CASTLE, including a unique tumor following breast-conserving surgery for early-stage breast invasive carcinoma. There were two female and one male. All three tumors were located in the right lobe of the thyroid, and one tumor showed extension into the surrounding soft tissue. Histologically, all tumors showed expansive growth and consisted of cords, nests or sheets of epithelial cells divided into irregularly shaped lobules by fibrous connective tissue with lymphoplasmacytic infiltration. Focal squamous differentiation resembling Hassall's corpuscles were observed. All cases stained positively for CD5, CD117, high molecular weight cytokeratin, cytokeratin, P63, carcinoembryonic antigen and epithelial membrane antigen. Positive staining for Bcl-2 in two cases and chromogranin A in one case was noted. Ki-67 expression ranged from 15 to 25%. Thyroid transcription factor and CD3 were negative. There was no evidence of recurrent or metastatic disease at following surgery. These features demonstrated CASTLE may arise from branchial pouch remnants, the thyroid solid cell nests. CASTLE is a rare entity, awareness of its occurrence as a second primary tumor is important to avoid overtreatment because it is associated with a favorable prognosis.

Potential Role of Adjuvant Radiation Therapy in Cervical Thymic Neoplasm Involving Thyroid Gland or Neck

PURPOSE

The purpose of this study is to assess the clinicopathologic features, treatment outcomes, and role of adjuvant radiation therapy (RT) in cervical thymic neoplasm involving the thyroid gland or neck.

MATERIALS AND METHODS

The medical and pathologic records of eight patients with cervical thymic neoplasm were reviewed retrospectively. All patients underwent surgical resection, including thyroidectomy or mass excision. Adjuvant RT was added in five patients with adverse clinicopathologic features. The radiation doses ranged from 54 Gy/27 fractions to 66 Gy/30 fractions delivered to the primary tumor bed and pathologically involved regional lymphatics using a 3-dimensional conformal technique.

RESULTS

Eight cases of cervical thymic neoplasm included three patients with carcinoma showing thymus-like differentiation (CASTLE) and five with ectopic cervical thymoma. The histologic subtypes of ectopic cervical thymoma patients were World Health Organization (WHO) type B3 thymoma in one, WHO type B1 thymoma in two, WHO type AB thymoma in one, and metaplastic thymoma in one, respectively. The median age was 57 years (range, 40 to 76 years). Five patients received adjuvant RT: three with CASTLE; one with WHO type B3; and one with WHO type AB with local invasiveness. After a median follow-up period of 49 months (range, 11 to 203 months), no recurrence had been observed, regardless of adjuvant RT.

CONCLUSION

Adjuvant RT after surgical resection might be worthwhile in patients with CASTLE and ectopic cervical thymoma with WHO type B2-C and/or extraparenchymal extension, as similarly indicated for primary thymic epithelial tumors. A longer follow-up period may be needed in order to validate this strategy.

Clinical analysis of thyroid carcinoma showing thymus-like differentiation: report of 8 cases

Thyroid carcinoma showing thymus-like differentiation (CASTLE) is a kind of rare neoplasm of the thyroid gland. Because thyroid CASTLE is rare and difficult to diagnose, its clinicopathologic features have not been well defined, and no universally accepted treatment recommendation is available. We analyzed retrospectively the clinicopathologic data of 8 patients with thyroid CASTLE who underwent surgery and radiotherapy at the Shengjing Hospital of China Medical University between December 2008 and June 2012. All patients accepted radical surgery. All patients accepted postoperative radiotherapy, except one 79-year-old patient. There was no evidence of recurrence or metastasis during the follow-up period. The pattern of immunohistochemical staining was similar to that of thymic carcinoma. Six of 8 CASTLE cases expressed CD5. All 8 CASTLE patients were negatively expressed in thyroglobulin, thyroid transcription factor 1, and calcitonin. Patients with thyroid CASTLE have good outcomes after radical resection and postoperative radiotherapy. Positive CD5 immunoreactivity can contribute to diagnosis of this disease.

Management of thyroid carcinoma showing thymus-like differentiation (CASTLE) invading the trachea

PURPOSE

To define the clinicopathological features and discuss the optimal management of carcinoma showing thymus-like differentiation (CASTLE).

METHODS

We retrospectively analyzed six patients with CASTLE.

RESULTS

The subjects comprised two men and four women (average age at initial diagnosis, 61 years, range 47-75 years). Preoperative biopsy yielded a correct diagnosis in two patients. Five patients underwent surgery and one was treated with radiation therapy alone. Four had extrathyroidal invasion and three had lymph node metastasis. During the clinical course, tracheal invasion was detected in five patients, the upper extent of the tumor being the lower half of the first tracheal ring. Two of these patients underwent tracheal sleeve resection. Two patients received postoperative radiotherapy for nodal metastasis, and one, after palliative surgery. The median follow-up period was 67 months (range 38-129). Recurrence was found 10 years post-therapy in the patient treated with radiation therapy only, resulting in death soon after. Although local recurrence was not found in the remaining five patients, new pulmonary metastases were diagnosed in the patient who underwent non-curative surgery.

CONCLUSIONS

CASTLE can be diagnosed preoperatively by core needle biopsy and CD5 staining. Curative resection with neck dissection followed by radiotherapy can yield a good outcome. Larynx-sparing complete resection may be more feasible for CASTLE, even though it has a higher incidence of tracheal invasion than differentiated thyroid carcinoma.

Cytologic Findings of Thyroid Carcinoma Showing Thymus-like Differentiation: A Case Report

Carcinoma showing thymus-like differentiation (CASTLE) is a rare carcinoma of the thyroid or adjacent soft tissue of the neck with a histologic resemblance to thymic epithelial tumors. Although the fine-needle aspiration (FNA) plays a central role in the initial evaluation of thyroid nodules, few reports about the cytologic findings of CASTLE have been found according to a review of literatures. We report cytologic findings of a case of CASTLE. A 34-year-old woman presented with a 2-month history of sore throat. The FNA showed that the smear was composed of three dimensional clusters and sheets. The tumor cells were round to ovoid with high nuclear : cytoplasmic ratios. The nuclei were vesicular with small nucleoli. There were some tumor cells showing keratinization. Some lymphocytes were found on the background and within clusters. The presence of poorly-differentiated tumor cells with a focal keratinization and a lymphocytic background on the FNA is suggestive of CASTLE.