Lymphoma-associated cryoglobulinemia
D. Test for serum cryoglobulin level
The key to the correct diagnosis is recognizing the subacute presentation of acral-predominant retiform purpura in a well-appearing patient with underlying lymphoma.
Retiform purpura can also present in ecthyma gangrenosum, a cutaneous syndrome that occurs when bacterial pathogens (commonly Pseudomonas aeruginosa) invade dermal vessels and cause neutrophilic cutaneous vasculitis.1 However, patients with ecthyma gangrenosum are usually septic and toxic-appearing, which is not the case in this patient. Patients with acute disseminated intravascular coagulation and cutaneous purpura are also generally ill-appearing and hemodynamically unstable. Some of them, especially those with the widespread purpura of purpura fulminans, can benefit from administration of protein C concentrate.2 However, disseminated intravascular coagulation is unlikely in this patient, given that she was otherwise well and her fibrinogen level and results of a coagulation panel were within normal limits. The calcium-phosphate product can be elevated in uremic calciphylaxis. However, extensive calciphylaxis typically involves fatty areas of the trunk and proximal extremities; involvement of the face and ears is atypical.