Metaplastic (infarcted) Warthin's tumour of the parotid gland: a possible consequence of fine needle aspiration biopsy

Aims: The metaplastic (or infarcted) variant of Warthin's tumour is charact erized by replacement: of much of the original oncocytic epithelium by meta plastic squamous cells, along with areas of extensive necrosis, fibrosis an d inflammatory change,The pathogenesis is unknown, but it is most likely to be vascular in origin, An association with a previous fine needle aspirati on (FNA) has been suggested, and this is explored further. Methods and results: Nine metaplastic Warthin's tumours were collected from several centres: all arose in the parotid gland, and all showed the charac teristic histological features. Eight had previously undergone FNA some 1-4 months before surgery; the other case had had an incisional biopsy. Conclusions: It is important to recognize metaplastic Warthin's tumour, bec ause the differential diagnoses of this benign neoplasm include mucoepiderm oid and squamous carcinoma, both primary and metastatic. The tumours in thi s study followed FNA or biopsy, and we believe this association is unlikely to be coincidental. Although many metaplastic Warthin's tumours clearly ar ise spontaneously, we conclude that the balance of probabilities favours th e view that FNA is capable of causing metaplastic change in a Warthin's tum our, and may have done so in these cases. If so, this previously unusual su btype will become increasingly common, as FNA becomes more widely used (and its value appreciated) in the investigation of patients with a mass in the neck.