MAML2 rearrangement as a useful diagnostic marker discriminating between Warthin tumour and Warthin-like mucoepidermoid carcinoma

Abstract

Warthin tumour is the second most common benign neoplasm of salivary glands. Despite its relatively characteristic histology, it may sometimes mimic other lesions. Here, we report two female non-smoker patients diagnosed with low-grade mucoepidermoid carcinoma with oncocytic epithelium and prominent lymphoid (Warthin-like) stroma and with molecularly confirmed MAML2 rearrangement. In addition, we screened a consecutive series of 114 Warthin tumour cases by means of MAML2 break apart fluorescence in situ hybridization to assess its value in differential diagnosis. MAML2 rearrangement was detected in both mucoepidermoid carcinoma cases, while all Warthin tumours were negative. Taking into account the literature data, Warthin-like mucoepidermoid carcinomas are more frequently observed in women, while a slight male predominance and smoking history are typical for Warthin tumour. In addition, the patients with Warthin-like mucoepidermoid carcinoma were significantly younger than those with Warthin tumour. To conclude, Warthin-like mucoepidermoid carcinoma may usually be suspected based on histology, while the diagnosis can be confirmed by means of molecular assays such as FISH. The investigation of MAML2 status is particularly advised when Warthin tumour is considered in a young, non-smoking, female patient.

Fine‑needle aspiration cytology of Warthin‑like mucoepidermoid carcinoma: A case report with cytological review

“…Radiological features were available for nine cases: Ultrasonography (9,11) and computed tomography (8,10,15) revealed a well-circumscribed tumour with multiple cysts. Magnetic resonance imaging displayed a low-or intermediate-intensity tumour (10)(11)(12)15). These features are consistent with those of conventional low-grade MEC (16).…”

“…The present study reported the sixth cytological Warthin-like MEC case. To the best of our knowledge, only 22 cases, including the present case, have been reported since the first report by Ishibashi et al (3) in 2015 (8)(9)(10)(11)(12)(13)(14)(15). Table I summarizes the clinicopathological features of Warthin-like MEC.…”

“…Intermediate cells are not observed in Warthin's tumour (17). (3,12,19) and are correlated with low-/intermediate-grade histology and improved prognosis (17,20). Fluorescence in situ hybridization using cellblock specimens is used for detecting MAML2 rearrangement in conventional MEC diagnosis (20); however, no such analysis for Warthin-like MEC using cytological specimens has been described.…”

Current Trends and Controversies in the Management of Warthin Tumor of the Parotid Gland

“…Microscopic foci of the conventional mucoepidermoid carcinoma exhibiting epidermoid and intermediate cells are often present and their identification aids in making the current diagnosis. In equivocal cases, the presence of a MAML2 rearrangement confirms the malignant diagnosis [24,25]. Another differential diagnosis of a WT includes oncocytoma and nodular oncocytic hyperplasia.…”

Molecular and Cellular Modelling of Salivary Gland Tumors Open New Landscapes in Diagnosis and Treatment

“…Both fusion products and EGF expression are used for diagnostic purposes to predict the outcome of the disease. FISH analysis of MALM2 rearrangement has been used to identify MEC in histological samples that strongly resembled Warthin’s tumor [ 81 , 82 ]. Chromosomal rearrangements have also been described in pleomorphic adenoma, such as the reciprocal translocations t (3;8) (p21;q12) resulting in promoter swapping between the zinc finger PLAG1 and the β-catenin gene [ 83 ].…”