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 characteris tics of 12 cases of a recently recognized entity, oncocytic papillary thyro id carcinoma (PC) with lymphoid stroma (Warthin-like tumour). Methods and results: The cases were retrieved from the surgical pathology f iles 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 immunohisto chemical 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 chai n reaction, in situ hybridization, and immunohistochemistry for Epstein-Bar r virus (EBV) detection revealed no significant positive signal. MIB-1 labe lling index was low, compatible with that of 'classical' PC. Conclusions: Warthin-like tumour is a rare Variant of PC, occurring predomi nantly in elderly women. Its histological features are distinct and well re cognizable, differentiating this tumour from a more aggressive tall-cell va riant of PC. The apparent indolent behaviour seems to be consistent with th e presence of dendritic/Langerhans cells and with low proliferative activit y. A possible role of EBV in pathogenesis of this lesion was not proven. Fu rther studies are necessary to determine the prognosis and metastatic poten tial of this neoplasm.