Unusual presentations of malignancy

Cancer symptoms usually arise from a direct effect of a primary tumour or its metastases. Uncommonly, malignancies may present through paraneoplastic syndromes (PNS). These are a heterogeneous group of disorders in which symptoms are caused by an indirect effect of the cancer. The relevance of these conditions is twofold: they may aid earlier diagnosis of malignancies, and may contribute to patient morbidity and mortality.