Cold agglutinin disease: A case report with atypical clinical findings.

A female in her 60s presented to the allergy and immunology clinic for further investigation of ongoing dermatitis. She presented with chronic acrocyanosis, mainly in her left lower extremity, extending distally from her mid thigh with concurrent ulcerations in her foot resulting in immobility secondary to pain. She experienced these symptoms for years without a definitive diagnosis. The lack of diagnosis was due, in part, to her atypical symptoms and laboratory findings that required a high level of clinical suspicion to diagnose. Extensive autoimmune workup was largely unrevealing with the exception of a cold agglutinin titer of 1:250 and a positive anticomplement C3b direct antiglobulin test. A diagnosis of cold agglutinin disease was made and treatment with rituximab monotherapy was initiated.