Oncocytic papillary carcinoma with lymphoid stroma (Warthin-like tumour) of the thyroid: a distinct entity with favourable prognosis

AIMS: We report the clinicopathological and immunohistochemical characteristics of 12 cases of a recently recognized entity, oncocytic papillary thyroid carcinoma (PC) with lymphoid stroma (Warthin-like tumour). Methods and results: The cases were retrieved from the surgical pathology files of our departments. There were 11 female patients and one male patient; they ranged in age from 45 to 85 years (mean 64.2 years). The immunohistochemical profile demonstrated positivity of tumour cells for cytokeratins, thyroglobulin, Leu-M1 and anti-mitochondrial antigen. S100 protein-positive stromal dendritic/Langerhans cells were uniformly present. Polymerase chain reaction, in situ hybridization, and immunohistochemistry for Epstein-Barr virus (EBV) detection revealed no significant positive signal. MIB-1 labelling index was low, compatible with that of 'classical' PC. CONCLUSIONS: Warthin-like tumour is a rare variant of PC, occurring predominantly in elderly women. Its histological features are distinct and well recognizable, differentiating this tumour from a more aggressive tall-cell variant of PC. The apparent indolent behaviour seems to be consistent with the presence of dendritic/Langerhans cells and with low proliferative activity. A possible role of EBV in pathogenesis of this lesion was not proven. Further studies are necessary to determine the prognosis and metastatic potential of this neoplasm.