Beyond the Tumor: Cutaneous Manifestations of Paraneoplastic Syndromes

The skin is the most visible organ of the human body and the second largest, surpassed only by the endothelium. Its functions extend beyond aesthetics, as it is considered the primary protective barrier against external agents such as microorganisms, corrosive substances, ultraviolet radiation, and other harmful vectors. It also plays crucial roles in preventing total body water loss and regulating temperature. This physical, immunological, and chemical barrier is essential for homeostasis and overall well-being. Additionally, the skin can serve as an early indicator of underlying neoplasms, being the epicenter of multiple manifestations of paraneoplastic syndromes. These syndromes represent a heterogeneous group of clinical manifestations caused by the release of substances by tumor cells or the body’s immune response to them. Paraneoplastic skin manifestations, such as acanthosis nigricans, Leser-Trélat syndrome, or necrolytic migratory erythema, are examples of how the skin can reflect systemic alterations related to cancer. The importance of the skin in this context lies in its accessibility for clinical evaluation and its ability to provide critical diagnostic clues. An attentive physician can identify cutaneous signs that act as “red flags”, guiding early cancer detection and potentially improving patient prognosis. Therefore, the skin is not only a barrier but also a reflection of internal health, playing a vital role in diagnosing systemic diseases and clinical oncology.