Ectopic right parietal pleural thymic carcinoma: a rare case and review of the literature

Head and neck squamous cell carcinomas of unknown primary: Can ancillary studies help identify more primary tumor sites?

A subset of head and neck squamous cell carcinomas present solely as metastatic disease in the neck and are of unknown primary origin (SCCUP). Most primary tumors will ultimately be identified, usually in the oropharynx. In a minority of cases, the primary site remains elusive. Here, we examine the role of ancillary testing, including mutational signature analysis (MSA), to help identify likely primary sites in such cases. Twenty-two cases of SCCUP in the neck, collected over a 10-year period, were classified by morphology and viral status; including human papillomavirus (HPV) testing by p16 immunohistochemistry (IHC) and RT-qPCR, as well as Epstein-Barr virus (EBV) testing by EBER-ISH. CD5 and c-KIT (CD117) IHC was done to evaluate for possible thymic origin in all virus-negative cases. Whole exome sequencing, followed by MSA, was used to identify UV signature mutations indicative of cutaneous origin. HPV was identified in 12 of 22 tumors (54.5%), favoring an oropharyngeal origin, and closely associated with nonkeratinizing tumor morphology (Fisher's exact test; p = 0.0002). One tumor with indeterminant morphology had discordant HPV and p16 status (p16+/HPV-). All tumors were EBV-negative. Diffuse expression of CD5 and c-KIT was identified in 1 of 10 virus-negative SCCUPs (10%), suggesting a possible ectopic thymic origin rather than a metastasis. A UV mutational signature, indicating cutaneous origin, was identified in 1 of 10 (10%) virus-negative SCCUPs. A cutaneous auricular primary emerged 3 months after treatment in this patient. Primary tumors became clinically apparent in 2 others (1 hypopharynx, 1 hypopharynx/larynx). Thus, after follow-up, 6 tumors remained unclassifiable as to the possible site of origin (27%). Most SCCUPs of the neck in our series were HPV-associated and thus likely of oropharyngeal origin. UV signature mutation analysis and additional IHC for CD5 and c-KIT for possible thymic origin may aid in further classifying virus-negative unknown primaries. Close clinical inspection of hypopharyngeal mucosa may also be helpful, as a subset of primary tumors later emerged at this site.

Carcinoma showing thymus-like differentiation of the parotid gland: The brief report of cytomorphology and review of the literature

Here, we report an extremely rare case of carcinoma with thymus-like differentiation (CASTLE) of the parotid gland. CASTLE is a rare malignant epithelial tumor with thymic epithelial differentiation that arises in the thyroid gland or perithyroidal soft tissue. CASTLE of salivary gland origin is rare, with only nine published case reports to date (reported as "CASTLE" or "thymic carcinoma"). It is critical to diagnose salivary gland tumors using fine needle aspiration cytology. However, this tumor is rare, and there have been few studies on its cytomorphological features. Therefore, it is important to understand the cytological diagnostic characteristics of CASTLE. Herein, we review the cytological features and diagnostic characteristics of salivary gland CASTLE. We also report the genotype results obtained using targeted exome sequencing, which we analyzed with DNA extracted from formalin-fixed paraffin-embedded tissue.

Ectopic Thymic Carcinoma Located on The Dorsal Side of The Thyroid Gland

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.

Ectopic cervical thymic squamous cell carcinoma misdiagnosed as thyroid cancer: a case report

Ectopic thymic neoplasm, particularly ectopic thymic carcinoma, is a rare disease that presents as a neck mass. Here, we present a case of ectopic thymic squamous carcinoma in a 65-year-old man who presented with persistent hoarseness. After fine needle aspiration cytology, the patient underwent total thyroidectomy with lymph node dissection. The final histopathological examination revealed the ectopic thymic squamous carcinoma. The patient was discharged without any postoperative complications. The patient received adjuvant radiation therapy and did not progress during the 1-year follow-up period.

Metastatic Ectopic Thymoma of the Neck without Mediastinal Involvement

Introduction

Thymoma is a rare malignancy with usual location in the antero-superior mediastinum. Occurrence of an extra-mediastinal thymic malignancy in the neck with lung metastasis and without involvement of the mediastinum is an extremely rare condition. Staging systems and treatment guidelines are defined for mediastinal thymomas but not for ectopically located thymomas.

Case Report

38-year-old female presented with the chief complaint of a progressive neck swelling, located predominantly in the right lateral neck, extending to the midline. Computed Tomography showed a heterogenous peripherally enhancing mass with likely origin from the thyroid gland. The mass measured 12 x 6 x 3.5 cm in size and extended from the hyoid bone superiorly to the suprasternal location inferiorly. Additionally, there were multiple, variable sized subpleural nodules scattered in both lungs, suggestive of lung metastases. Histopathology and immunohistochemistry findings from neck mass confirmed the diagnosis of Thymoma Type A.

Conclusions

Thymoma is a rare tumor that typically does not show aggressive behaviour. Extra-mediastinal neck thymoma with bilateral lung metastasis is an extremely rare presentation. Thymoma presenting as neck swelling without mediastinal extension on radiology, poses a diagnostic dilemma. Histopathology with immunohistochemistry helps to confirm the final diagnosis. Surgery is the mainstay for the management of localized tumors with adjuvant treatment reserved for incompletely resected tumors or advanced stage. Systemic metastasis are rare in this indolent tumor and chemotherapy regimens are investigational. Clinical presentation, prognostic factors, staging and management guidelines are still not well defined for this rare tumor with atypical location.

Ectopic thymic carcinoma of the parotid gland

Ectopic thymic carcinoma (ETC) of the parotid gland is a rare entity. This report describes the case of a 52-year-old man with a painless mass in the right parotid gland. Magnetic resonance imaging (MRI) showed a biphasic mass consisting of a central segment and a peripheral segment. The patient underwent a superficial parotidectomy, and point-to-point correspondence sampling for analysis based on MRI findings was performed. The pathological finding was ETC, and there was an excellent association between MRI characteristics and histopathological findings. Subsequently, the patient underwent postoperative radiation therapy. At the 9-month follow-up, he had recovered well without facial paralysis, and there was no evidence of recurrence or metastasis. This report describes the clinical, radiological, and pathological features of the ETC.

Ectopic thymoma: report of 2 cases and review of the literature

In this report, we present two cases of ectopic thymoma, aiming to explore the clinicopathologic features, diagnosis, and differential diagnosis of ectopic thymoma. Case 1 was a female 56-years-old. For 6 months' time, there was no obvious cause of cough, expectoration, chest tightness, or asthma with chest pain. PET-CT showed a right middle lung and lower lung mass with increased FDG metabolism. Postoperative pathology was diagnosed as right middle and lower lung ectopic thymoma, type B2, invading the chest wall. Case 2 was a male of 54-years-old. By physical examination the right chest cavity had a mass present for 1 week and he was admitted to hospital. Postoperative pathology was diagnosed as right thoracic ectopic thymoma, type AB. No recurrence has been found to in the follow-up of these two patients. In conclusion, ectopic thymoma occurs outside the anterior mediastinum. It is rare, the clinical symptoms are not typical, and pre-operative diagnosis is difficult. It is easily misdiagnosed as other diseases. Surgical treatment is the best method. According to the pathologic type and invasion of the tumor, radiotherapy may be considered.

Ectopic thymic carcinoma in parotid gland: a rare case and review of literature

Thymic carcinoma that occurs outside the anterosuperior mediastinum is rare. To date, only five cases of ectopic thymic carcinoma have been reported in the English-language literature. Here, we report a case of 43-year-old Chinese man who suffering from ectopic thymic carcinoma of the parotid gland. Magnetic resonance imaging (MRI) showed a round soft tissue mass in the parotid gland. After enhancement, it showed the edge of the tumor was rough, with irregular shallow lobes. Histological examination (HE) showed tumor cells were invasive, and partially arranged in a lobulated structure. These characteristics were similar to previous English-language literature reports. Immunohistochemical (IHC) examination showed that tumor cells were positive for CD5, CD117 and p63, which confirms this case is ectopic thymic carcinoma. Postoperatively the patient received combined paclitaxel plus carboplatin chemotherapy. Currently, no evidence of metastasis or recurrence has been found in this patient.