The biopsy specimen showed extravasated red blood cells and numerous occluded superficial dermal vessels, some with fibrin thrombi and hyalinization of vessel walls (Figure 2 and Figure 3).
A full hypercoagulation workup was performed and was notable for hyperhomocysteinemia due to a compound heterozygote mutation in the methylenetetrahydrofolate reductase (MTHFR) gene (heterozygous for variants 677C>T and 1298A>C). The workup was otherwise negative for protein C and S deficiencies, antithrombin 3 deficiency, factor V Leiden, and lupus anticoagulant.