Rare and changeable as a chameleon: paraneoplastic syndromes in renal cell carcinoma

Paraneoplastic syndromes (PNS) in renal cell carcinoma (RCC) are important to be recognized by the treating physician, because they may lead to diagnosis of underlying malignant disease. On the other hand, PNS may dominate the clinical picture and can hide the true disorder like a chameleon. When realized, a PNS can be used as a 'neoplastic tumour marker', especially in case of recurrence. Their occurrence can even be linked to prognosis of disease.

A PubMed search combining the MeSH terms renal cell carcinoma and paraneoplastic syndrome was executed in April 2015. All hits concerning these MeSH terms have been taken into account when writing this review.

There is a big gap between reporting and incidence of paraneoplastic syndromes in renal cell carcinoma. Most of the articles in Medline are case reports and reviews of research done in the 1950s-1990s. One problem is that a clear definition of a paraneoplastic syndrome is still lacking. The most important PNS in RCC are hypercalcemia. It is important that PNS are not only arising in advanced stages of renal cell carcinoma; in contrast, a PNS can often be the first symptom of RCC.

Paraneoplastic syndromes are often unrecognized but are important biomarkers in RCC. Further research into the underlying pathomechanisms of PNS may improve our understanding of the RCC tumour biology and is urgently needed.