Intrasalivary Thymic Carcinoma: A Case Report and Literature Review

Neuroendocrine neoplasms of head and neck, genitourinary and gynaecological systems, unknown primaries, parathyroid carcinomas and intrathyroid thymic neoplasms: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up

•This Clinical Practice Guideline provides key recommendations for managing rare endocrine tumours. •Neuroendocrine neoplasms of different origins, parathyroid carcinoma and intrathyroid thymic neoplasms are included. •The guideline covers clinical imaging and pathological diagnosis, staging and risk assessment, treatment and follow-up. •The authors comprise a multidisciplinary group of experts from different institutions and countries in Europe. •Recommendations are based on available scientific data and the authors’ collective expert opinion.

Parotid Gland Tumors: Molecular Diagnostic Approaches

Parotid gland pathology represents a web of differential diagnoses. There are many complex cases that require extensive diagnostic tests for a complete and correct final pathology diagnosis. Currently the official classification of parotid gland tumors extends over more than 40 subtypes. We performed a query of the PubMed database regarding the use of molecular biology tests in performing a better characterization of the tumors in specific cases. By using fluorescence in situ hybridization (FISH), reverse transcription polymerase chain reaction (RT-PCR) or next-generation sequencing, the team managing complex cases can offer a personalized therapeutic solution. We review the molecular differential diagnosis according to published articles in the last 5 years for many types of parotid gland tumors ranging from benign to borderline malign tumors to malign aggressive tumors. Mucoepidermoid carcinoma is a distinct subtype of parotid malignancy that was the subject of a consistent number of articles. However, the molecular biology diagnosis techniques helped more in excluding the diagnosis of mucoepidermoid carcinoma, and probably retrospectively limiting the number of cases with this final diagnosis. In Romania, the molecular biology diagnosis is available only in limited research facilities and should receive more consistent funding that will make it available on a larger scale. The novelty of this scoping review is that we propose an algorithm for molecular differential diagnosis of the tumors that could be encountered in the parotid gland.

The differential diagnosis of lymphoepithelial lesion of the salivary gland

The differential diagnosis of salivary gland lesions with epithelial components and lymphoid stroma is often challenging. Salivary gland carcinoma with tumor-associated lymphoid proliferation, tumors composed of both epithelial and lymphoid components, lymphoid neoplasms in the salivary gland, and inflammatory lesions are all included in this category. It encompasses inflammatory lesions and neoplastic lesions. With the exception of Warthin tumors, these lesions are rare, making them more difficult to diagnose. Carcinoma showing thymus-like elements has recently been reported in the salivary gland. Similar to thymic carcinoma, tumor cells are positive for CD5 and are accompanied by T lymphocytes.

The basaloid-spectrum of salivary gland tumors: A focused review with practical diagnostic considerations

Basaloid salivary gland neoplasms are a diverse and varied group of benign and malignant tumors. The term 'basaloid' is broadly used in reference to cells with elevated nuclear to cytoplasmic ratio, sparse cytoplasm, and hyperchromatic nuclei. However, a subset may also fit within the "small round blue cell tumor" morphologic category or the "biphasic" salivary gland tumor category. Furthermore, there are no established thresholds for the proportion of basaloid tumor cells needed to consider a tumor within the basaloid spectrum. Given the implicit variability in what is considered a basaloid salivary gland tumor, one may question the inclusion of certain entities (canalicular adenoma, HMGA2::WIF1 pleomorphic adenoma, polymorphous adenocarcinoma) in this review based on classic morphologic features. However, salivary gland tumors with even minor basaloid components may appear 'basaloid' in small biopsy specimens and, thus, a choice was made to focus on common and uncommon diagnostic differentials with this in mind. Entities that will be covered in this review also include basal cell adenoma and basal cell adenocarcinoma, adenoid cystic carcinoma, lymphoepithelial carcinoma, sialoblastoma, adamantinoma-like Ewing Sarcoma, NUT carcinoma, and carcinoma showing thymus-like differentiation.

Expression of CD5 in salivary gland tumors: an ancillary marker for carcinoma showing thymus-like differentiation (CASTLE) of the major salivary gland

Recently, cases of carcinoma showing thymus-like differentiation (CASTLE) occurring in major salivary glands have been identified. To assess the diagnostic value of CD5 immunohistochemistry in distinguishing salivary CASTLE from other types of salivary gland tumors, we evaluated CD5 expression in 109 salivary gland tumors, encompassing 23 different histological types, including salivary CASTLE. In addition, we reviewed 10 previously reported cases of salivary CASTLE. Most salivary CASTLE cases (10/11, 91%) showed strong CD5 expression. In contrast, 104 of 108 (96%) non-salivary CASTLE tumors were negative for CD5, while the remaining four tumors (3.7%), all of which were histologically Warthin tumors, showed focal positivity for CD5 with weak to moderate intensity. In conclusion, the findings in this study support the potential use of CD5 immunohistochemistry for distinguishing salivary CASTLE from other histological types of salivary gland tumors. Aberrant CD5 expression in this tumor may be linked to the tumor microenvironment.

Carcinoma showing thymus-like elements (CASTLE) with amyloid deposition in the parotid gland

Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

TOETVA: a single surgeon's learning curve and a case report of CASTLE thyroid tumor

BACKGROUND

Owing to the lack of visible scars, the transoral endoscopic thyroidectomy vestibular approach (TOETVA) offers superior aesthetic outcomes compared to conventional thyroidectomy. Carcinoma showing thymus-like differentiation (CASTLE) represents a rare thyroid gland neoplasm. This study aimed to explore the TOETVA learning curve and present a case report of CASTLE.

METHODS

A study with precise 1:1 matching was conducted to assess the procedure safety and cancer control outcomes of TOETVA in comparison to conventional surgery between May 2020 and May 2023. Cumulative sum analysis was employed to optimally fit the learning curve. Subsequently, a case report of CASTLE treated with TOETVA surgery was presented.

RESULTS

The mean operative time was longer in the TOETVA group than in the open group. The TOETVA group had a higher incidence of skin numbness and excellent cosmetic outcomes compared to the open group. The learning curves for work area preparation, unilateral thyroid lobectomy, and the entire surgical process were 59, 28, and 50 cases, respectively. There were no differences between the learning and proficient groups, except for operative time, intraoperative blood loss, and drainage volume on the first postoperative day.

CONCLUSIONS

A comprehensive analysis of the TOETVA learning curve utilizing cumulative and analytical methods demonstrated the feasibility of TOETVA with regards to surgical integrity, safety, and oncological safety. This study's findings suggest that a surgeon's cumulative number of TOETVA cases exceeding 50 can reach the mastery stage. Moreover, diagnosing CASTLE is challenging and necessitates immunohistochemical detection of relatively specific markers associated with thymic epithelial tumors.

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.

Undifferentiated Large Cell Carcinoma of the Thymus Associated with Plasma-Cell Type Castleman Disease-Like Reaction: A Case Series

Undifferentiated large cell carcinoma of the thymus with a Castleman disease (CD)-like reaction is a thymic carcinoma accompanied by an inflammatory reaction closely resembling the morphological features of CD. This disease is extremely rare and distinctive, only five cases have been documented in a single report, and all five cases were associated with a reaction like the hyaline vascular type CD. For the first time, we report two cases of undifferentiated large cell carcinoma of the thymus with a plasma cell type CD-like reaction. The two cases presented similar histological findings and immunoprofiles. Undifferentiated large cells were arranged in nests and cords within hyperplastic follicles, mimicking pseudogerminal centers. Abundant plasma cells were distributed in the interfollicular areas. The tumor cells were positive for CK-pan and BRG1 staining but negative for CD5, CD117, CK5/6, p63, p40, and EBER. Therefore, the diagnoses of squamous cell carcinoma, lymphoepithelial carcinoma, or micronodular thymic carcinoma with lymphoid hyperplasia were excluded. Even though the carcinoma cells showed high-grade nuclear pleomorphism with prominent nucleoli, these two cases presented indolent clinical courses, which were consistent with the previous report.