Differential Diagnosis between Oral Metastasis of Renal Cell Carcinoma and Salivary Gland Cancer

Lingual metastasis as the first presentation of clear cell renal cell carcinoma: Report of a rare case clinically mimicking a benign lesion

Metastases in the oral cavity are rare and frequently associated with widespread disease and poor prognosis. Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma (RCC), known for its propensity for metastatic spread. The diagnosis of oral metastases from ccRCC is challenging, especially when the patient has no history of primary neoplasm. Herein, we reported a rare metastatic ccRCC in a 58-year-old female presenting clinically as a painless nodule on the tongue mimicking a benign lesion. Microscopically, the tumor showed a proliferation of clear cells organized in nests with a predominantly lobular arrangement. The dense connective tissue stroma was highly vascularized, exhibiting some areas with a hyalinized aspect. Immunohistochemistry showed focal positivity for pan-cytokeratin AE1/AE3 and strong positivity for CK8, CK18, epithelial membrane antigen (EMA), vimentin, and CD10. S-100 protein, HMB-45, CK7, and CK20 were negative. The definitive diagnosis was metastatic ccRCC. The treatment was initiated with sunitinib. However, the disease progressed, and the patient was submitted to palliative care. Despite the low survival rate of patients with metastases, the clinician's experience in identifying an oral metastatic lesion may reveal undiagnosed primary tumors and provide better prognosis and survival rates.

Pleomorphic Adenoma of the Salivary Glands and Epithelial–Mesenchymal Transition

Pleomorphic adenoma (PA) is a localized tumor that presents pleomorphic or mixed characteristics of epithelial origin and is interwoven with mucoid tissue, myxoid tissue, and chondroid masses. The literature reported that PA most often occurs in adults aged 30–60 years and is a female predilection; the exact etiology remains unclear. Epithelial–mesenchymal transition (EMT) is the transdifferentiation of stationary epithelial cells primarily activated by a core set of transcription factors (EMT-TFs) involved in DNA repair and offers advantages under various stress conditions. Data have suggested that EMTs represent the basic principle of tissue heterogeneity in PAs, demonstrating the potential of adult epithelial cells to transdifferentiate into mesenchymal cells. It has also been reported that multiple TFs, such as TWIST and SLUG, are involved in EMT in PA and that SLUG could play an essential role in the transition from myoepithelial to mesenchymal cells. Given this background, this review aims to summarize and clarify the involvement of EMT in the development of PA, chondrocyte differentiation, and malignant transformation to contribute to the fundamental elucidation of the mechanisms underlying EMT.

Clear Cell Neoplasms of Salivary Glands: A Diagnostic Challenge

This review focuses on the heterogenous group of clear cell neoplasms of salivary glands and attempts to identify major differential diagnostic features. Within the head and neck region, clear cells are found most commonly in salivary gland tumors, but may also be seen in tumors of squamous or odontogenic epithelial origin, primary or metastatic carcinomas, benign or malignant melanocytic lesions, or benign or malignant mesenchymal tumors. Clear cells occur fairly commonly among a wide variety of salivary gland neoplasms, but mostly they constitute only a minor component of the tumor cell population. Clear cells represent a major diagnostic feature in two salivary gland neoplasms, epithelial-myoepithelial carcinoma and hyalinizing clear cell carcinoma. In addition, salivary gland neoplasms composed predominantly of clear cells could also include clear cell variants of other salivary neoplasms, such as mucoepidermoid carcinoma and myoepithelial carcinoma, but their tumor type-specific histologic features may only be available in limited nonclear cell areas of the tumor. Diagnosing predominantly clear cell salivary gland tumors is difficult because the immunoprofiles and morphologic features may overlap and the same tumor entity may also have a wide range of other histologic presentations. Many salivary gland tumors are characterized by tumor type-specific genomic alterations, particularly gene fusions of the ETV6 gene in secretory carcinoma, the MYB and MYBL1 genes in adenoid cystic carcinoma, the MAML2 gene in mucoepidermoid carcinoma, the EWSR1 gene in hyalinizing clear cell carcinoma, and others. Thus, along with conventional histopathologic examination and immunoprofiling, molecular and genetic tests may be important in the diagnosis of salivary gland clear cell tumors by demonstrating genetic alterations specific to them.

Application of Contrast-Enhanced Ultrasound Combined with Elastic Imaging Technology in Differential Diagnosis of Salivary Gland Tumors

This paper proposes the effect of contrast-enhanced ultrasound combined with real-time elastic imaging technology in the differential diagnosis of salivary gland tumors. 200 patients were selected, including 120 males and 60 females. The age ranged from 9 to 83 years, with an average of 55.4 years. Among the 200 cases, there were 90 cases of single parotid gland on the right, 77 cases of single parotid gland on the left, 2 cases of bilateral (single parotid gland on each side), 2 cases of multiple parotid gland on the right (2 lesions), 1 case of 2 lesions on the left and 1 lesion on the right, and 1 case of multiple parotid gland on the left (4 lesions). 135 cases were located in the superficial lobe (78%) and 38 cases (22%) in the deep lobe of parotid gland. The ARIETTA 70 color Doppler ultrasound diagnostic instrument is used. The equipment is equipped with high-frequency contrast probe, real-time elastic imaging technology, and related software. The results showed that the detection rate of salivary gland tumors by ultrasound was 100% and the diagnostic coincidence rate was 71% (123/173). Ultrasound can not only identify the tumors in and around the parotid gland but also identify the location, size, and internal structure of the tumors. Combined with CDFI, it can make qualitative diagnosis of most benign and malignant salivary gland tumors and provide help for clinical treatment and operation plan. It is proved that contrast-enhanced ultrasound and real-time elastic imaging technology have advantages over gray-scale ultrasound in differentiating benign and malignant superficial enlarged lymph nodes, and the combined use can effectively improve the diagnostic efficiency.

Clear Cell Renal Cell Carcinoma Metastasized to the Ampulla of Vater 16 Years after Nephrectomy—A Rare Case

Although clear cell renal cell carcinoma (ccRCC) is easy to diagnose early and most can be radically resected, nearly one-third of patients still experience metastases after radical nephrectomy. The most common distant metastases sites of ccRCC are lung, bone and liver. However, periampullary metastasis of ccRCC is very rare and easy to misdiagnose. A 59-year-old male patient was hospitalized for recurrent hematochezia. He had a history of nephrectomy 16 years ago due to ccRCC. Enhanced upper abdominal computed tomography (CT) suggested a mass in the ampulla of vater, and active hemorrhage of duodenal papilla was observed by endoscopy. He underwent an emergency pancreaticoduodenectomy because endoscopic hemostasis and transcatheter arterial embolization (TAE) both failed. Intraoperatively, we found that the tumor located in the ampulla and invaded the pancreatic tissue. The operation was successful, with no postoperative complications. Postoperative pathology suggested metastatic ccRCC.