Abstract
Kidneys and skin are seldom considered associated, but their relationship is more closer than generally believed. In some immunological diseases (SLE...) and genetic syndromes (tuberous sclerosis, Fabrys disease...) the cutaneous manifestations are integral parts of the clinical picture. In advanced uremia, besides the well-known itching skin lesions, calciphylaxis may appear, a typical example of cutaneous involvement secondary to the metabolic complications (calcium-phosphate imbalance) of the renal disease. Nephrogenic systemic fibrosis appears only in patients with renal failure and it has a very severe prognosis due to the systemic organ involvement. Moreover, there is a heterogeneous group of metabolic diseases, with renal involvement, that may be accompanied by skin lesions, either related to the disease itself or to its complications (diabetes mellitus, porphyrias). In systemic amyloidosis, fibrils may deposit even in dermis leading to different skin lesions. In some heroin abusers, in the presence of suppurative lesions in the sites of needle insertion, renal amyloidosis should be suspected, secondary to the chronic inflammation. Atheroembolic disease is nowadays frequently observed, as a consequence of the increasing number of invasive intravascular manoeuvres. Skin manifestations like livedo reticularis or the blue toe syndrome are the most typical signs, but often renal dysfunction is also present. In all these conditions, the skin lesion may be a first sign, a warning, that should arouse the suspicion of a more complex pathology, even with renal involvement. Being aware of this relationship is fundamental to accelerate the diagnostic process.
