Metastasising pleomorphic salivary gland adenoma presenting as synchronous pulmonary and hepatic metastases

Pleomorphic salivary adenomas (PAs) are the commonest benign tumours of glandular origin in the head and neck. Occasionally PAs undergo malignant transformation to carcinoma-ex-PA and can metastasise. More rarely they metastasise without malignant transformation of the primary tumour. We present a case of a benign pleomorphic salivary gland adenoma, presenting 7 years later with multiple liver metastases and a synchronous pulmonary metastasis. Histological analysis of the lung and liver lesions confirmed a diagnosis of metastasising pleomorphic adenoma (MPA). The lung lesion was fully excised, but the multifocal nature of the liver lesions rendered them inoperable. The patient is being managed conservatively and to date has no local recurrence of the primary salivary gland tumour or any further metastases. To the best of our knowledge this is the first case of MPA with simultaneous metastasis to both lungs and liver, and also the first to describe multiple liver metastases.