Rocky Mountain spotted fever complicated by gangrene: report of six cases and review.

Although mortality due to fulminant Rocky Mountain spotted fever (RMSF) is well appreciated, the ability of the disease to cause survivors to become permanently disabled is not as widely known. We report six cases of RMSF complicated by gangrene. Although four patients required multiple limb and/or digital amputations, only one death resulted. Our review of the English-language literature revealed 23 additional cases of RMSF complicated by gangrene. Pathophysiologically, gangrene is most likely related to small-vessel occlusion. Skin necrosis and gangrene in association with RMSF are the extreme end on a continuum from reversible to irreversible skin and tissue damage caused by Rickettsia rickettsii. Most patients with RMSF have a typical skin rash that resolves without sequelae. Some patients develop minute cicatrices marking the location of focal cutaneous necrosis; for other patients, digital ischemia occurs transiently or evolves to produce severe ischemic changes without gangrene that result in permanent impairment. At the far end of this clinical continuum are patients who develop gangrene requiring amputation.