Metastatic tumours to the oral cavity - pathogenesis and analysis of 673 cases

The oral region is an uncommon site for metastatic tumour cell colonization and is usually evidence of a wide spread disease. In 25% of cases, oral metastases were found to be the first sign of the metastatic spread and in 23% it was the first indication of an undiscovered malignancy at a distant site. The jawbones, particularly the mandible, were more frequently affected than the oral soft tissues (2:1). In the oral soft tissues, the attached gingiva was the most commonly affected site (54%). The major primary sites presenting oral metastases were the lung, kidney, liver, and prostate for men, breast, female genital organs (FGO), kidney, and colo-rectum for women. The primary site differs according to oral site colonization, in men the lung was the most common primary site affecting both the jawbones and oral mucosa (22% and 31.3%, respectively) followed by the prostate gland in the jawbones (11%) and kidney in the oral soft tissues (14%). In women, the breast was the most common primary tumour affecting the jawbones and soft tissues (41% and 24.3%, respectively), followed by the adrenal and female genital organs (FGO) in the jawbones (7.7%) and FGO in the soft tissues (14.8%). The clinical presentation of the metastatic lesions differ between the various sites in the oral region. In the jawbones most patients complain of swelling, pain and paresthesia which developed in a relative short period. Early manifestation of the gingival metastases resembled a hyperplastic or reactive lesion, such as pyogenic granuloma, peripheral giant cell granuloma, or fibrous epulis. Because of its rarity, the diagnosis of a metastatic lesion in the oral region is challenging, both to the clinician and to the pathologist, in recognizing that a lesion is metastatic and in determining the site of origin. The clinical presentation of a metastatic lesion in the oral cavity can be deceiving leading to a misdiagnosis of a benign process, therefore, in any case where the clinical presentation is unusual especially in patients with a known malignant disease a biopsy is mandatory.