An Uncommon Presentation of Vasopressin-Induced Purpura Fulminans.

Purpura fulminans (PF) is a rarely encountered rapidly evolving dermatological manifestation of ischemia, particularly in critically ill patients. Considered one of the very few dermatological emergencies, it has high mortality rate where patients often succumb to the illness. It can manifest in three forms: neonatal, idiopathic, and the more commonly infectious variety, which can be secondary to mostly bacterial and rarely viral etiology. It is also reported to be highly associated with disseminated intravascular coagulation (DIC), heparin-induced thrombocytopenia (HIT), and acute hepatic failure (AHF). Hereditary or acquired deficiency of protein C and dysregulation of the coagulation cascade, mainly protein C-thrombomodulin, has been implicated in the pathogenesis. We present a 55-year-old male admitted to the intensive care unit for diabetic ketoacidosis (DKA) and septic shock. Along with initiating management protocol for DKA and broad-spectrum antibiotics, he was initially started on norepinephrine for septic shock. Because of persistent refractory septic shock, he was subsequently initiated on phenylephrine and vasopressin to maintain adequate perfusion. The following day, he was found to have sharply demarcated blackish non-blanching discoloration on bilateral knees, lower limbs, and scrotum, sparing the acral regions. This cutaneous manifestation persisted throughout his hospital course, although it improved after discontinuation of vasopressin while continuing with other pressors. Vasopressin has been implicated in a few instances of skin necrosis; however, PF has rarely been documented and never within 1 day like ours. This case demonstrates a unique development of PF likely from vasopressin after ruling out the diagnoses of DIC, HIT, thrombotic thrombocytopenic purpura, and AHF.