Paraneoplastic syndromes in patients with primary oral cancers: a systematic review

The aim of this study was to review all the paraneoplastic syndromes of primary tumours of the oral cavity. Metastatic tumours of the mouth and primary tumours of the oropharynx (including tonsils), and major salivary glands were excluded. The primary search was conducted on PubMed, Scopus and EMBASE, and included every paraneoplastic syndrome from a primary oral tumour described in English, French, or German papers during the last 20 years. The secondary search was conducted by handpicking articles from reviews on paraneoplastic syndromes of the head and neck. The aim of the tertiary search was to identify conditions that had been reported only rarely. We then cross-referenced "mouth neoplasm" with every paraneoplastic condition cited in relevant review articles. We classified the paraneoplastic syndromes that arose from tumours of the head and neck into six categories: endocrine, dermatological, vascular and haematological, rheumatoid, ocular, and neurological. The following conditions are described in this review: syndrome of inappropriate antidiuretic hormone production, hypercalcaemia, hypercalcaemia-leucocytosis syndrome, ectopic production of beta-human chorionic gonadotrophin, Bazex syndrome, Sweet syndrome, tripe palm syndrome, pemphigus, pityriasis rotunda, neutrophilic leukemoid reaction, cerebral venous sinus thrombophlebitis, digital ischaemia, dermatomyositis, necrotising myopathy, autoimmune retinal degeneration, and subacute cerebellar degeneration. Paraneoplastic syndromes of the oral cavity are a heterogeneous group. Most syndromes occur from squamous cell carcinoma and their aetiology is poorly understood. They are important to recognise as they can be the presenting complaint of a malignant tumour, change the prognosis, and considerably reduce the quality of life.