A 74F w/ ESRD on HD, DM comes with in a painful rash that has grown over 3 weeks.
Diagnosis in ESRD: Calciphylaxis!
*Description: “painful black eschar with slight surrounding angulated purpura”
*Associated with elevated calcium-phosphorous product
*Due to calcium deposition in vessels -> distal ischemia -> tissue necrosis
*Prognosis 60 to 80% in 1 year, often due to infectious complications
Differential diagnosis of black eschar: think infections (mostly fungal) and vascular (see http://www.evernote.com/l/AHam3_xniGtPorodk6Z4TZLnAFiU_EAi9lM/ )
-Fungal: Aspergillus, mucormycosis, cryptococcus
-Bacterial: Pseudomonas ecthyma gangrenosum, anthrax