The ulcerous form directly linked to ESRD is the so-called calciphylaxis or calcied uraemic arteritis (CUA). This is a rare ulcerous form often with an inauspicious prognosis, which begins with necrotic cutaneous ulcerations with unde­ned edges (Fig.33.4) and can spread extensively (see Chap. 14). Recognised risk factors for CUA include diabetes mellitus, poorly controlled sec­ondary hyperparathyroidism along with the use of calcium-based phosphorus binders, obesity, female gender, history of RRT, white ethnicity, low albumin level, and impairment of the vitamin K pathway because of warfarin use [17]. CUA leads to substantial morbidity, prolonged hospi­talisation, and mortality rates as high as 80%. The clinical presentation is frequently character­ised by the development of proximal (and often symmetrical) lesions on the buttocks, thighs, and abdomen with less common involvement of the acral regions. Nonhealing wounds provide an opportunity for infection with multiple microor­ganisms and sepsis.