Soft‐tissue gangrene secondary to mixed cryoglobulinemia

A 61-year-old Hispanic male with chronic hepatitis C presented with a 4-week history of a nonpruritic skin rash involving his lower extremities, hands, arms, and right ear. He also reported purple discoloration of his right foot, along with pain in the extremity that worsened with ambulation. Physical examination revealed diffuse purpura of both arms and legs (Figure 1). The right foot was cold to the touch and purple to black in color (Figure 2). There were multiple skin ulcers of various sizes covering the anterior aspect of his legs bilaterally. Pedal pulses were 2/4. Laboratory evaluation revealed positive cryoglobulins with low C4 and CH50 concentrations of 3 mg/dL (1040) and 2 units/mL (60-144), respectively. Other immunological studies were negative. Lower extremity arterial Doppler studies were normal. His clinical and laboratory findings were attributed to mixed cryoglobulinemia, and treatment, consisting of daily intravenous methylprednisolone, a single dose of intravenous cyclophosphamide, and plasmapheresis, was initiated. Despite these interventions, 5 days later, he developed severe burning pain in the right extremity with worsening discoloration and a line of demarcation at the level of his proximal midfoot. Eventually, right below the knee, amputation was performed, and histopathological examination