Mucoepidermoid carcinoma in Warthin tumor of the parotid gland

Pathogenesis of Warthin's Tumor: Neoplastic or Non-Neoplastic?

Warthin's tumor is the second most frequent neoplasm next to pleomorphic adenoma in the salivary gland, mostly in the parotid gland. The epithelial cells constituting a tumor are characterized by the presence of mitochondria that undergo structural and functional changes, resulting in the development of oncocytes. In addition to containing epithelial cells, Warthin's tumors contain abundant lymphocytes with lymph follicles (germinal centers) that are surrounded by epithelial cells. The pathogenesis of Warthin's tumor is not fully understood, and several hypotheses have been proposed. The risk factors for the development of Warthin's tumor, which predominantly occurs in males, include aging, smoking, and radiation exposure. Recently, it has been reported that chronic inflammation and aging cells promote the growth of Warthin's tumor. Several reports regarding the origin of the tumor have suggested that (1) Warthin's tumor is an IgG4-related disease, (2) epithelial cells that compose Warthin's tumor accumulate mitochondria, and (3) Warthin's tumor is a metaplastic lesion in the lymph nodes. It is possible that the pathogenesis of Warthin's tumor includes mitochondrial metabolic abnormalities, accumulation of aged cells, chronic inflammation, and senescence-associated secretory phenotype (SASP). In this short review, we propose that DNA damage, metabolic dysfunction of mitochondria, senescent cells, SASP, human papillomavirus, and IgG4 may be involved in the development of Warthin's tumor.

Salivary Duct Carcinoma Arising in a Warthin Tumor of the Parotid Gland: A Rare Case Report with Review of Literature and PD-L1 Expression

Warthin's tumor is the second most common neoplasm of the parotid gland and consists of 2 components, including lymphoid stroma and glandular epithelium. Malignant transformation in this tumor is mostly seen in the lymphoid component; however, the carcinomatous transformation of the epithelial component is extremely rare. Cases of latter reported in the literature include squamous cell carcinoma, adenocarcinoma, mucoepidermoid carcinoma, oncocytic carcinoma, Merkel cell carcinoma, and undifferentiated carcinoma. We describe an extremely rare case of salivary duct carcinoma arising in a Warthin tumor in a 64-year-old male. Patient presented with an enlarging left parotid mass, biopsy of which showed salivary duct carcinoma. He subsequently underwent left parotidectomy along with left level II-IV lymph node dissection. Histology revealed both in situ as well as invasive salivary duct carcinoma arising from Warthin tumor. Immunohistochemistry showed tumor cells positive for CK7, AR, and GATA3, while p63 highlighted the myoepithelial cell layer in the in situ component. Her2 was 2+ by immunohistochemistry. In addition, PD-L1 IHC revealed positive expression with a combined positive score of 20%.

Warthin-like mucoepidermoid carcinoma and mucoepidermoid carcinoma, mucinous metaplasia involving Warthin tumor: three case reports

Warthin-like mucoepidermoid carcinoma (MEC) is a recently identified MEC variant of the salivary gland. MEC morphologically mimics Warthin tumor (WT) but harbors the same chromosomal translocation t (11; 19) (q21; p13) as MEC. Thus, differential diagnosis is crucial. MEC involving WT is extremely rare in salivary glands. In this study, we reported a case of Warthin-like MEC, a case of MEC co-existing with WT, and a case of mucinous metaplasia in WT. We also discussed the possible link between WT and MEC.

The potential role of follicular helper T cells and helper T cells type 1 in Warthin tumour

Warthin tumour (WT) is a benign tumour of the salivary gland that proliferates in both glandular epithelial and lymphoid tissue components, and rarely exhibits cystic changes. T follicular helper cells (Tfh) are involved in the formation and maintenance of germinal centres, the differentiation of B cells into plasma cells, and the maintenance of helper T cell type 2 (Th2)-dominant humoral immune responses. T-bet induces differentiation into helper T cell type 1 (Th1) by suppressing differentiation into Tfh and enhances cellular immune responses. The objective of this study was to enhance our understanding of the immune responses and relationship between Tfh and Th1 cells in patients with WTs. In this study, we classified WTs (n = 64) into solid-type (n = 25) and cyst-type (n = 39). We also performed immunostaining of the Tfh markers CXCR5 and CD40 L, and the Th1 marker T-bet for statistical analysis. The cyst-type exhibited significant atrophy of the germinal centre area (P = 0.0019), significantly fewer Tfh-positive lymphocytes in germinal centres (P < 0.0001), and significantly more T-bet-positive lymphocytes in the epithelium (P = 0.0017). We observed that Tfh were involved in the formation and maintenance of lymphoid follicles in WTs. In the cyst-type, Th2-dominant humoral immune responses were suppressed, and Th1-dominant cellular immune responses may have caused damage to tumour tissue.

Prevalence of Lymphoid Neoplasia in a Retrospective Analysis of Warthin Tumor: A Single Institution Experience

Warthin tumor is one of the most common benign salivary gland tumors. Overt lymphoma is known to occur in the lymphoid stroma of Warthin tumor. In situ follicular neoplasia is difficult to identify in routine histologic examination of lymphoid tissue and has not been reported in association with Warthin tumor. Our objective is to determine the prevalence of overt malignant lymphoma and in situ follicular neoplasia in Warthin tumor. We conducted a retrospective histological evaluation of 89 sequential Warthin tumor cases with available slides and blocks from the years 2010-2019. Of these, 84 cases were subjected to immunohistochemical testing, while 5 cases had been previously worked up for the suspicion of lymphoma. We identified two additional cases of lymphoid neoplasia associated with Warthin tumor including small lymphocytic lymphoma/chronic lymphocytic leukemia (n = 1) and in situ follicular neoplasia (n = 1) in addition to previously reported case of follicular lymphoma included in this study. The prevalence rate of first-time detected lymphoid neoplasia in Warthin tumor is 3.4%. The prevalence rate of overt lymphoma is 2.2%, while the prevalence of in situ follicular neoplasia is 1.1%. We propose histologic criteria to identify small lymphocytic lymphoma and follicular lymphoma in Warthin tumor. These include a monotonous interfollicular expansion of small lymphocytes and germinal centers composed of a monotonous population of lymphocytes without polarity or tingible body macrophages respectively. It is very important for pathologists to perform a diligent morphological examination and perform immunohistochemistry in suspected cases to identify subtle involvement of Warthin tumor by lymphoma. In patients with involvement of Warthin tumor by in situ follicular neoplasia, concurrent lymphoma in the same tissue and other sites should be considered. Patients without overt lymphoma elsewhere likely have a low risk of progression to follicular lymphoma. The low prevalence of in situ follicular neoplasia in Warthin tumor, combined with the low rate of clinical progression to lymphoma, make routine screening of Warthin tumor for in situ follicular neoplasia unnecessary.

Warthin-like mucoepidermoid carcinoma of the parotid gland: a diagnostic and therapeutic dilemma

Mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland tumor. Although the parotid gland is the most common site of involvement, other major salivary glands and the minor salivary glands—most commonly of the palate—also can be involved. The management of mucoepidermoid carcinoma depends on the grade of the tumor and the adequacy of resection. We present the case of a 56-year-old female presenting a painless progressive cheek mass over 2 months. Imaging and fine-needle aspiration cytology provided the diagnosis of Mucoepidermoid carcinoma. A superficial parotidectomy was done, and the histopathology revealed a predominantly cystic tumor with a bilayered epithelium of oncocytic and basal cells. Moderate nuclear pleomorphism with infiltration of atypical squamous cells in few glandular cysts was seen. Special staining revealed the presence of intracellular mucin. A diagnosis of Warthin-like variant of MEC was made, based on these findings. After the surgical procedures, the patient is disease-free at 8 months of follow-up. The Warthin-like variant is a rare variant of MEC with fewer than 10 cases described in the English literature. Various differential diagnoses include the malignant transformation of Wartin tumor (WT), squamous metaplasia of WT, and metastasis from a distant primary. We emphasize the role of routine microscopy in identifying rare variants of common malignancies. Even though translocation studies are helpful in diagnosis, the typical histopathological findings should confirm it.

Mucoepidermoid Carcinoma in Warthin Tumor of the Parotis in Childhood: A Case Report and Review of the Literature

Mucoepidermoid carcinoma arising in Warthin tumor of the parotid gland is an extremely rare entity. This is so far described only in the adult age group, and only one patient has been reported in the pediatric age group until today. Herein, we describe our patient and review the literature. This was a case of a 9-year-old girl admitted with a painless swelling in the left side of her face for at least 2 weeks. Histopathologic examination of total parotidectomy specimens revealed mucoepidermoid carcinoma arising in the Warthin tumor. This case is the youngest patient reported to date.

Follicular Lymphoma Diagnosed in Warthin Tumor: A Case Report and Review of the Literature

Warthin tumor is one of the most common benign salivary gland tumors. It is unusual and difficult to diagnose follicular lymphoma within the lymphoid tissue of Warthin tumor. We present a rare case of a 69-year-old man with systemic follicular lymphoma initially diagnosed in a Warthin tumor. Lymphomas occurring within Warthin tumors are rare, however, follicular lymphoma is most commonly reported. Because these patients require further treatment depending on the stage of a disease, it is important for a pathologist to review the histology of Warthin tumors diligently to identify occult lymphomas.

Infarcted Warthin tumor with mucoepidermoid carcinoma-like metaplasia: a case report and review of the literature

Background

Warthin tumor is a common, benign, painless salivary gland neoplasm. Rarely, Warthin tumors show large areas of squamous metaplasia; such Warthin tumors are called metaplastic or infarcted Warthin tumors because they are occasionally accompanied with tumor necrosis. The histological distinction between mucoepidermoid carcinomas and the metaplastic portions of Warthin tumors can be challenging; without a genetic study, mucoepidermoid carcinomas can be misdiagnosed as metaplastic Warthin tumors. We report a case of infarcted Warthin tumor partly showing mucoepidermoid carcinoma-like epithelial metaplasia. Only two cases of infarcted Warthin tumor similar to our case have been reported.

Case presentation

A 69-year-old Japanese man presented with a right parotid tumor. He had noticed the swelling on his right buccal region 1 year previously; the lesion had rapidly enlarged, with associated pain, 1 month previously. A radiological examination revealed a mass in the tail of the right parotid gland. Superficial parotidectomy was performed. On histological examination, the mass showed typical focal features of Warthin tumor; other areas showed coagulation necrosis of the tumor. These areas were surrounded by non-oncocytic epithelium comprising squamous and mucinous epithelial cells. Although cellular atypia of the non-oncocytic epithelium was not observed, a mixture of squamous and mucinous cells and lack of abundant lymphoid tissue mimicked low-grade mucoepidermoid carcinoma. Based on the results of fluorescence in situ hybridization, MAML2 gene rearrangement was not present in the typical portions of Warthin tumor and the mucoepidermoid carcinoma-like lesion. Therefore, a metaplastic or infarcted Warthin tumor was diagnosed. Our patient was disease-free 8 months after surgery.

Conclusions

Clinicians need to know that pain is a clinical symptom of infarcted/metaplastic Warthin tumor. Pathologists should be aware that a metaplastic Warthin tumor can mimic a low-grade mucoepidermoid carcinoma. Our case showed a mucoepidermoid carcinoma-like lesion that was confined near the area of tumor necrosis, and neither cytological atypia nor apparent invasive growth was present. These findings appeared to be histological clues of a metaplastic Warthin tumor rather than a mucoepidermoid carcinoma. Careful clinicopathological evaluation as well as genetic studies are needed to clarify the distinction between mucoepidermoid carcinoma and metaplastic portions of Warthin tumors.

MAML2 Rearrangements in Variant Forms of Mucoepidermoid Carcinoma: Ancillary Diagnostic Testing for the Ciliated and Warthin-like Variants

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. Recent studies have shown that most MECs harbor gene fusions involving MAML2-an alteration that appears to be specific for MEC, a finding that could be diagnostically useful. While most cases of MEC are histologically straightforward, uncommon variants can cause considerable diagnostic difficulty. We present 2 variants of MEC for which MAML2 studies were crucial in establishing a diagnosis: a previously undescribed ciliated variant, and the recently described Warthin-like variant. All cases of ciliated and Warthin-like MEC were retrieved from the archives of The Johns Hopkins Hospital. Break-apart fluorescence in situ hybridization for MAML2 was performed on all cases. One ciliated MEC and 6 Warthin-like MECs were identified. The ciliated MEC presented as a 4.6 cm cystic lymph node metastasis originating from the tongue base in a 47-year-old woman. The Warthin-like MECs presented as parotid masses ranging in size from 1.2 to 3.3 (mean, 2.7 cm) in 4 women and 2 men. The ciliated MEC consisted of macrocystic spaces punctuated by tubulopapillary proliferations of squamoid cells and ciliated columnar cells. The Warthin-like MECs were comprised of cystic spaces lined by multilayered oncocytic to squamoid cells surrounded by a circumscribed cuff of lymphoid tissue with germinal centers. In these cases, the Warthin-like areas dominated the histologic picture. Conventional MEC, when present, represented a minor tumor component. MAML2 rearrangements were identified in all cases. Warthin-like MEC, and now a ciliated form of MEC, are newly described variants of a common salivary gland carcinoma. Unfamiliarity with these novel forms, unanticipated cellular features (eg, cilia), and morphologic overlap with mundane benign processes (eg, developmental ciliated cysts, Warthin tumor) or other carcinomas (eg, ciliated human papillomavirus-related carcinoma) may render these variants susceptible to misdiagnosis. These unusual variants appear to consistently harbor MAML2 fusions-a finding that establishes a clear link to conventional MEC and provides a valuable adjunct in establishing the diagnosis.

Mucoepidermoid carcinoma arising in Warthin's tumor of the parotid gland: Clinicopathological characteristics and immunophenotypes

Mucoepidermoid carcinoma (MEC), an extremely rare tumor, arises from the epithelial component of preexisting parotid Warthin tumors (WT). Among the 309 cases of surgically resected WTs in Chinese PLA General Hospital and Beijing Shijitan Hospital of Capital Medical University, 5 cases (1.6%) fulfilled the criteria for MECs transformed from WTs. Clinicopathological characteristics of MECs was demonstrated in order to avoid misdiagnosis of this rare type of tumor. All the 5 patients, 3 males and 2 females, presented painless masses in the parotid gland. MECs were located inside or at the edge of WTs, with an obvious transitional zone between WT and MEC. Basal cells of WTs and epidermoid cells of MECs were strongly positive for cytokeratin CK5/6, CK34βE12, and P63; whereas negative for CK7, CK20, and CEA. Mucous cells of MECs were positive for CK7, CEA, as well as periodic acid-Schiff (PAS), whereas negative for CK5/6, CK34βE12, CK20, and P63. MECs patients were followed up for 25–69 months after surgery, presenting no evidence of recurrence or metastasis. Collectively, MECs arising from WT is very rare. The pathological diagnosis was based on histological morphology, especially the transitional zone between WT and MEC.