Clear cell carcinoma, not otherwise specified/hyalinising clear cell carcinoma of the salivary gland: The current nomenclature, clinical/pathological characteristics and management

Hyalinizing clear cell carcinoma of the sublingual gland: A case report and literature review

RATIONALE

Hyalinizing clear cell carcinoma (HCCC) of the salivary glands is a rare low-grade malignant tumor. This type of tumor is particularly uncommon in the sublingual glands.

PATIENT CONCERNS

A 57-year-old female with a mass on the left side of the floor of the mouth that had been present for 2 months. The computed tomography scan of the neck revealed a nodular abnormal density shadow in the left sublingual area, measuring approximately 2.6 cm × 1.9 cm.

DIAGNOSES

Primary HCCC of the sublingual gland.

INTERVENTIONS

The patient underwent surgical treatment and reconstruction using a left anterolateral femoral free flap, which showed immunohistochemical positivity for CK 5/6, CK 7, CK (AE1/AE3), and Ki-67 (<5%), but negative for SMA and S-100.

OUTCOMES

No recurrence was observed during the 12-month postoperative follow-up period.

LESSONS

The absence of characteristic clinical manifestations makes HCCC highly susceptible to misdiagnoses. This case presents a rare instance of HCCC in the sublingual gland, providing a reference for the clinical diagnosis and treatment of the disease.

Pulmonary salivary gland tumor-hyalinizing clear cell carcinoma: a literature review

Primary pulmonary hyalinizing clear cell carcinoma (HCCC) is a very rare lung tumor that accounts for less than 0.09% of all primary lung tumors and has no specific epidemiology. The correct diagnosis requires imaging, laboratory, pathological, immunohistochemical, and molecular examination. The most typical feature of pulmonary HCCC is the clear cell component with clear stroma. In addition, the fusion gene EWSR1::ATF1 due to t(12;22)(q13;q12) is essential for the pathological diagnosis of pulmonary HCCC. The main treatment for pulmonary HCCC is surgery. This review focus on the pathological features, immunohistochemical examination, mutation analysis and treatment of pulmonary HCCC.

Genome Doubling Shapes High-Grade Transformation and Novel EWSR1::LARP4 Fusion Shows SOX10 Immunostaining in Hyalinizing Clear Cell Carcinoma of Salivary Gland

Hyalinizing clear cell carcinoma (HCCC) is a rare indolent malignant tumor of minor salivary gland origin with EWSR1::ATF1 rearrangement. Pathologically, the tumor cells possess a clear cytoplasm in a background of hyalinized stroma. Generally, the tumor cells are positive for p63 and p40 and negative for s100 and α-smooth muscle actin, suggesting that they differentiate into squamous epithelium and not into myoepithelium. In this study, we performed a detailed histopathological and genomic analysis of 6 cases of HCCC, including 2 atypical subtypes-a case of "high-grade transformation" and 1 "possessing a novel partner gene for EWSR1." We performed a sequential analysis of the primary and recurrent tumor by whole-exome sequencing, RNA sequencing, Sanger sequencing, and fluorescence in situ hybridization to investigate the effect of genomic changes on histopathology and clinical prognosis. A fusion gene involving the EWSR1 gene was detected in all cases. Five cases, including the "high-grade transformation," harbored a known EWSR1::ATF1 fusion gene; however, 1 case harbored a novel EWSR1::LARP4 fusion gene. This novel EWSR1::LARP4-fused HCCC has a SOX10-positive staining, which is different from the EWSR1::ATF1-fused HCCC. According to whole-exome sequencing and fluorescence in situ hybridization analysis, the "whole-genome doubling" and focal deletion involving CDKN2A, CDKN2B, and PTEN were detected in HCCC with "high-grade transformation." Conclusively, we identified a novel partner gene for EWSR1, LARP4, in indolent HCCC. Importantly, "high-grade transformation" and poor prognosis were caused by whole-genome doubling and subsequent genomic aberrations.

Primary pulmonary hyalinizing clear cell carcinoma with pseudopapillary structures and abundant cysts filled with mucus

Pulmonary hyalinizing clear cell carcinoma (HCCC) is a new and rare form of lung salivary gland tumor. Only twenty-two cases have been reported in the literature to date. Furthermore, their clinicopathological features have not been fully characterized. In this paper, we describe the clinicopathological characteristics, immunohistochemical features, and molecular genetic changes in two HCCC cases. We also simultaneously reviewed related literature on similar cases reported. Of the two cases, one was of a 58-year-old man with a 4.3 cm lung tumor, which was the largest among all previously reported cases. The tumor showed an infiltrative growth pattern and perineural and vascular invasion microscopically. Moreover, nuclear grooves, high mitotic figures, and comedo necrosis were observed in addition to classic morphological features. More importantly, rare pseudopapillary structures were observed. The second case was of a 60-year-old woman in whom the tumor was mainly composed of multiple cysts filled with mucus. The remaining focal solid areas of the tumor comprised clear and acidophilic cells embedded in the hyalinizing stroma. Immunohistochemical analysis revealed that the tumor cells of both cases were positive for CK5/6, p40, and p63 expression, but negative for napsin A, TTF-1, and SOX10 expression. The HCCC diagnosis in both cases was validated by fluorescence in-situ hybridization (FISH) examination, which showed Ewing sarcoma breakpoint region 1-activating transcription factor 1 (EWSR1-ATF1) gene fusion. Primary pulmonary HCCC is a rare lung tumor originating from the bronchial mucosa, and its histological features may vary, such as rare pseudopapillary structures and abundant cysts. Thus, the diagnosis should be a combined analysis of histopathological characteristics with immunophenotype and molecular examination, including EWSR1-ATF1 gene fusion detection.

Clinicopathological and molecular study of 10 salivary gland clear cell carcinomas, with emphasis on rare cases with high grade transformation and occurring in uncommon sites

Background

As a rare salivary gland malignancy, clear cell carcinoma (CCC) is easily misdiagnosed. This study identified the features that allow better recognition of the clinicopathological and molecular characteristics and the prognosis of CCC, focusing on high-grade transformation (HGT) in this tumor and cases arising in uncommon sites.

Methods

Clinicopathological and follow-up data for 10 CCC samples were retrieved. Immunohistochemical (IHC) staining was performed, and fluorescence in situ hybridization (FISH) was used to detect EWSR1 gene rearrangements, EWSR1–ATF1 gene fusions, and MAML2 gene rearrangements.

Results

Histologically, typical CCCs comprised bland polygonal or round cells with clear cytoplasm. In contrast with typical CCCs, HGT tumor cells exhibited nuclear pleomorphism, high nuclear-to-cytoplasmic ratios, high mitotic activity, and necrosis. Rare morphologic features such as pseudopapillae, gland-like spaces, and entrapped ducts were also observed. Occasionally, tumors involving the oral cavity might arise from the overlying epithelium of the mucosal surface. Immunohistochemically, all the cases expressed p63, p40, and CK5/6, while myoepithelial-related markers were uniformly negative in all cases. HGT exhibited a wild type p53 expression pattern. FISH demonstrated EWSR1 rearrangement (10/10) and EWSR1–ATF1 fusion (4/5); however, MAML2 remained intact (0/3).

Conclusions

CCCs with HGT or occurring in uncommon sites are extremely rare. Combining morphology based IHC and molecular detection provided reliable evidence that the HGT component represented a transformation of CCC rather than the coexistence of another tumor and helped differentiating CCCs in uncommon sites from their mimics, avoiding potential misdiagnosis and inappropriate therapy. The overall prognosis for CCCs is good, except for the HGT cases, which needed continued treatment.

Mutational and immunologic Landscape in malignant Salivary Gland Tumors harbor the potential for novel therapeutic strategies

Salivary gland carcinomas (SGC) are rare (3-6 % of all head and neck cancers) and show biological heterogeneity depending on the respective histological subtype. While complete surgical resection is the standard treatment for localized disease, chemotherapy or radiation therapy are frequently insufficient for the treatment of unresectable or metastasized SGC. Therefore, new therapeutic approaches such as molecularly targeted therapy or the application of immune checkpoint inhibition enhance the treatment repertoire. Accordingly, comprehensive analyses of the genomic landscape and the tumor-microenvironment (TME) are of crucial importance in order to optimize and individualize SGC treatment. This manuscript combines the current scientific knowledge of the composition of the mutational landscape and the TME in SGCs harboring the potential for novel (immune-) targeted therapeutic strategies.

Clear cell carcinoma: a comprehensive literature review of 254 cases

This comprehensive literature review represents a summary of all cases of clear cell carcinoma (CCC) of the salivary glands that are documented in the literature. PubMed was used to collect available reports of CCC; 97 reports detailing 254 cases, published between 1983 and 2020, were retrieved. Clinically the tumor manifests most commonly as a painless mass or swelling on the palate, and the duration of symptoms prior to seeking care ranges from 1 week to 6 years. Local tumor recurrence was present in 18.8% of the cases. By histopathology, CCC shows a mixture of growth patterns including solid (25.1%), nested (78.6%), sheet-like (23.5%), cords (46.1%), and trabeculae (42.4%). Immunohistochemical studies are positive for one or more cytokeratins (99.1%), PAS (95.1%), EMA (77.8%), and p63 (96.3%), but negative for S-100 (96.3%), PASD (91.1%), SMA (91.0%), and calponin (95.1%). Molecular features were reported in 113 cases; 96.0% were positive for an EWSR1 rearrangement by EWSR1 break apart FISH testing and 14.8% were positive for the rearrangement EWSR1-ATF1 tested by qPCR or targeted RNA sequencing. Clinical patterns and genetic studies imply that this tumor is the extraosseous counterpart of clear cell odontogenic carcinoma, an intraosseous odontogenic tumor of the jaws.

Molecular Pathology of Salivary Gland Neoplasms: Diagnostic, Prognostic, and Predictive Perspective

Salivary gland neoplasms are an uncommon and widely heterogeneous group of tumors. In recent years, there has been considerable progress in efforts to reveal the molecular landscape of these tumors, although it is still limited and appears to be only the tip of the iceberg. Genomic aberrations, especially specific chromosomal rearrangements including CRTC1-MAML2 and CRTC3-MAML2 in mucoepidermoid carcinoma, MYB-NFIB and MYBL1-NFIB fusions in adenoid cystic carcinoma, PLAG1 and HMGA2 alterations in pleomorphic adenoma and carcinoma ex pleomorphic adenoma, ETV6-NTRK3 and ETV6-RET in secretory carcinoma, EWSR1-ATF1 and EWSR1-CREM in clear cell carcinoma, provide new insights into the molecular pathogenesis of various salivary gland neoplasms and help to better classify them. These genetic aberrations primarily serve as diagnostic tools in salivary gland tumor diagnosis; however, some also have promise as prognostic or predictive biomarkers. This review summarizes the latest developments in molecular pathology of salivary gland tumors with a focus on distinctive molecular characteristics.

Epithelial-Myoepithelial Carcinoma

Epithelial-myoepithelial carcinoma is an uncommon low-grade salivary gland carcinoma. It is classically characterized by biphasic tubular structures composed of inner eosinophilic ductal cells and outer clear myoepithelial cells. In addition, epithelial-myoepithelial carcinoma sometimes shows various histologic features, including a cribriform pattern, basaloid appearance, and sebaceous differentiation. Because clear myoepithelial cells are also noted in other benign and malignant salivary gland tumors, the histologic variety and similarity with other tumor entities make the diagnosis of epithelial-myoepithelial carcinoma challenging. A recent analysis revealed that HRAS hotspot point mutations are specifically identified in epithelial-myoepithelial carcinoma and the assessment of given genes facilitate the correct diagnosis.

An unusual case of hyalinizing clear cell carcinoma in a sinonasal cavity and cranial base

Hyalinizing clear cell carcinoma (HCCC) is a rare, predominantly minor salivary gland tumor. Most of these tumors occur in the oral cavity, mainly the palate and tongue. Primary localization of the tumor in the region of the nasal cavity and paranasal sinuses is extremely rare and, with only a few cases reported in the literature so far. We present an extremely rare case of a 61-year-old woman with hyalinizing clear cell carcinoma (HCCC), occupying the left posterior nasal and nasopharyngeal cavity, as a primary tumor location. The patient total recovery was uneventful, and she is now free of disease at three years postoperative follow-up.

Salivary gland hyalinizing clear-cell carcinoma with cutaneous metastasis: A rare and deceptive tumor

Clear-cell carcinoma (CCC) is an uncommon malignant tumor of minor salivary glands. It characteristically has a low-grade morphology and a favorable outcome by most reports. An EWSR1-ATF1 fusion can be detected in the majority of cases. We present a rare case of CCC, which had an aggressive course with the development of cutaneous metastases. Practicing dermatopathologists should be aware of this tumor given its low-grade appearance and histopathologic resemblance to other primary cutaneous adnexal and metastatic neoplasms.

Does Nodal Metastasis and Perineural Invasion Affect Local Control in Hyalinizing Clear Cell Carcinoma of the Oral Cavity? A Case Report with Long Term Follow-Up

Hyalinizing clear cell carcinoma (HCCC) is a rare, low-grade neoplasm accounting for approximately 1% of salivary gland neoplasms. Histologically, it is characterized by a monomorphous population of clear cells arranged in sheets, nests, or cords, lacking ductal structures. Until recently, clear cell carcinoma of the oral cavity (OC) represented a diagnosis of exclusion when other head and neck pathologic entities such as epithelial-myoepithelial carcinoma or mucoepidermoid carcinoma could be ruled out, making definitive diagnosis by light microscopy and immunoprofiling a challenge. As a result, initial biopsies are often misclassified, and could result in under- or overtreatment. More recently, the presence of the EWSR1-ATF1 gene fusion has been adopted to definitively diagnose HCCC. Typically, HCCC demonstrates clinical indolence and responds well to curative surgical excision alone for localized disease, with adjuvant radiotherapy (RT) reserved for high risk features including perineural invasion, lymphovascular invasion, and regional cervical metastasis. The literature, however, lacks consensus regarding the role of adjuvant radiotherapy. In this article, we report a case of HCCC in a rare site involving the ventral tongue, with high risk features of perineural invasion and cervical nodal metastasis. The patient underwent surgical excision alone; declining adjuvant radiotherapy despite the high risk features, and was alive with no evidence of disease at the 42-month mark. Furthermore, we provide an update on the current prognostic indicators for HCCC, and emphasize the need for chromosomal analysis to achieve a definitive diagnosis.

Hyalinizing Clear Cell Carcinoma: Base of Tongue

Hyalinizing clear cell carcinoma (HCCC) is a low grade, rare neoplasm originating from the minor salivary glands. It usually follows an indolent course and the main treatment modality is surgery. The prognosis of these tumours are good, hence it needs to be differentiated from other carcinomas with clear cells. Here we report a pathologically proven HCCC of the base of tongue.

EWSR1 translocation in primary hyalinising clear cell carcinoma of the thymus

AIMS

In thymic carcinomas, focal clear cell change is a frequent finding. In addition to a prominent, diffuse clear cell morphology, some of these carcinomas show an exuberant hyalinised extracellular matrix, and therefore probably represent a separate entity. However, a characteristic genomic alteration remains elusive. We hypothesised that, analogous to hyalinising clear cell carcinomas of the salivary gland, hyalinising clear cell carcinomas of the thymus might also harbour EWSR1 translocations.

METHODS AND RESULTS

We identified nine archived cases of thymic carcinoma with focal clear cell features and two cases that showed remarkable hyalinised stroma and prominent, diffuse clear cell morphology. These two cases expressed p40 and were negative for Pax8, CD5, and CD117. Programmed death-ligand 1 was highly positive in one case (70%), and negative in the other one. EWSR1 translocation was identified in both cases of hyalinising clear cell carcinoma, and was absent in all nine carcinomas that showed clear cell features without substantial hyalinisation. In one of the EWSR1-translocated cases, a fusion between exon 13 and exon 6 of EWSR1 and ATF1, respectively was identified by next-generation sequencing.

CONCLUSIONS

These findings suggest that the EWSR1 translocation and possibly the EWSR1-ATF1 fusion might be unifying genomic alterations for thymic clear cell carcinomas with prominent hyalinised stroma, for which we propose the term 'hyalinising clear cell carcinoma of the thymus'. Because the immunophenotype is unspecific, testing for the EWSR1 translocation might be helpful in discriminating this entity from other thymic neoplasms or metastases, in particular those with clear cell change.

Salivary Clear Cell Carcinoma Clinicopathologic Characteristics and Outcomes: A Population-Based Analysis

Background:

Salivary clear cell carcinoma is an uncommon, low-grade malignancy for which limited data describing predictive clinicopathologic factors and treatment outcomes exist because of rarity.

Methods:

The authors queried the Surveillance, Epidemiology, and End Results database from 1982 to 2014. Multivariate Cox and Kaplan-Meier analyses were performed to determine disease-specific survival (DSS) and predictive clinicopathologic factors.

Results:

One hundred ninety-eight patients with salivary clear cell carcinoma were included. Overall incidence was 0.011 per 100 000 individuals, with no significant annual percentage change across years (−0.93%, P = .632). Five-, 10-, and 20-year DSS rates were 81.3% (n = 117), 69.6% (n = 94), and 55.3% (n = 68), respectively. Men (hazard ratio, 4.74; P = .0087) and patients with regional (hazard ratio, 5.59; P = .018) or distant (hazard ratio, 8.9; P = .01) metastases carried a worse prognosis. Five-year DSS was greater in patients with localized disease (96.36%, P < .0001) than those with regional or distant metastases. Treatment with surgery alone had better 10-year DSS (86.3%) compared with treatment with combination radiation and surgery (57.6%) or radiation monotherapy (18.75%, P < .0001).

Conclusions:

Salivary clear cell carcinoma carries an overall good prognosis. Patients with localized disease and those treated with surgery alone have more favorable prognoses. Male patients and those with regional or distant metastatic disease at time of presentation carry a worse prognosis.

Level of Evidence:

N/A

Hyalinizing clear cell carcinoma of salivary gland origin in the head and neck: clinical and histopathological analysis

Hyalinizing clear cell carcinoma (HCCC) is an extremely rare neoplasm of salivary gland origin with a low-grade indolent nature. It is difficult to distinguish from other malignant salivary gland tumours. Clinical outcomes following surgery are generally reported as good. The aim of this study was to further determine the features of HCCC. This study was approved by Medical ethics review of affiliated hospital of jiangsu university. Fourteen new cases of HCCC are reported. The clinical and histopathological data of these 14 cases were analysed alongside those of 141 cases identified in a systematic review of the literature (up to 2016). Demographic data, histopathological findings, clinical presentation, primary treatment, and outcomes were extracted. Histologically, HCCC tumour cells had a clear cell morphology with hyalinized stroma. Immunohistochemical results were positive for cytokeratins and EMA, but negative for SMA, S100, vimentin, and calponin. Twelve of the 14 patients showed EWSR1 translocation. Local nodal metastasis on presentation was present in 17.3% and the overall recurrence rate was 17.7% in the total population (N=155), compared with 35.7% and 21.4%, respectively, in the new cases alone. Focal necrosis and local metastasis were identified as possibly associated with recurrence. The overall prognosis was good: only 3.8% of patients died of the disease. HCCC is less indolent than was previously thought, but overall the prognosis is good. Risk factors for recurrence may include focal necrosis and local metastasis at presentation. The best treatment for patients with HCCC is wide local excision combined with regional lymph node dissection.

Primary paranasal sinus hyalinizing clear cell carcinoma: a case report

Background

Hyalinizing clear cell carcinoma (HCCC) is a rare low-grade tumour of salivary glands that was first described as a distinct entity in 1994 by Milchgrub et al. EWSR1-ATF1 fusion was found to be specific for this tumour. The majority of the reported cases of HCCC arise from minor salivary glands within the oral cavity. Primary HCCC of the paranasal sinus is extremely uncommon. To our knowledge, only three cases have been reported in the English literature. Herein, we present a case of HCCC of the posterior ethmoid/maxillary sinus.

Case presentation

A 63-year-old lady who presented with a long history of epistaxis. CT scan revealed a destructive mass in the left ethmoid/posterior maxillary sinus extending to the nasal cavity. Surgical excision was done and microscopic evaluation showed a tumour composed mainly of nests of clear epithelial cells separated by fibrocellular and hyalinized septa with extensive bone destruction. The tumour cells expressed CK5/6, EMA and p63 immunohistochemically but were negative for S100 protein, PAX-8, RCC and CK7. Sinonasal renal cell–like adenocarcinomas, myoepithelial carcinoma and metastatic renal cell carcinoma were excluded by radiological and immunohistochemical studies. Fluorescence in situ hybridization analysis revealed an EWSR1 gene rearrangement. Postoperative radiation was administrated and the patient did not show recurrence or distant metastasis 4 months after the surgery.

Conclusion

Head and neck region have many tumours that demonstrate clear cell changes on histology. Thus, the differential diagnosis for HCCC is wide. Awareness of this rare entity and the possibility of it is arising in unusual location is necessary. EWSR1-AFT1 fusion, a consistent finding in HCCC, can be used to confirm the diagnosis.