Warthins tumor: Cyto histological spectrum with emphasis on diagnostic difficulties

Warthins tumour is characterized by the presence of epithelial proliferation in a lymphoid stroma. It has been categorized as Sieferts types: 1-4, depending on the proportions of the 2 components. Although FNA is fairly accurate in establishing the diagnosis, the cytologic diagnosis of this tumor has potential sources of error. This retrospective study was conducted in the Department of Pathology and Lab Medicine, of a tertiary care hospital. Cytology and surgical pathology records of past 15 years were screened. A total of 1200 FNAC cases of salivary gland lesions in the past 15 years were retrieved. 36 cases with presumptive cytodiagnosis of WT were identified and histopathological correlation was done. Histopathological correlation could be done in 24 cases. 19 out of 24 cases, were confirmed as WT. The 5 cases with discordance were analyzed for potential diagnostic pitfalls. The most common discordance was in the category of papillary proliferation with minimal lymphoid infiltrate. One case proved as oncocytoma and the other was papillary oncocyticcystadenoma. The other major pitfalls, were the interpretation of atypical squamoid cells. Their presence in a lymphoid background needs consideration of cytologic diagnosis of WT, mucoepidermoid carcinoma and metastatic squamous carcinoma. FNA showed an accuracy of 79% for WT. Cytological misinterpretation can thus occur in presence of morphology other than classical Siefert type1. An awareness of these potential pitfalls should push the need for avoiding single cytologic interpretation.