An 80-year-old man presented to our clinic with a 7-month history of purple discoloration, numbness and pain of the left third and fourth digits (Figure 1A). His other hand and his feet were unaffected. The discoloration was exacerbated by cold exposure but did not return to normal colour or show paroxysmal pallor, ruling out Raynaud phenomenon. He had a history of well-controlled diabetes, was not hypertensive and did not smoke. His body mass index was 19.7. Laboratory investigations were as follows: hemoglobin 10.6 (normal 13.5-17.6) g/dL, reticulocyte count 6.4% (normal 0.6%-2.0%), indirect bilirubin 1.2 (normal 0.2-0.9) mg/dL, lactate dehydrogenase 514 (normal 106-211) IU/L, reduced haptoglobin, elevated immunoglobulin M (IgM) 526 (normal 33-190) mg/dL, hemagglutination on blood smear (Appendix 1, available at www.cmaj.ca/lookup/doi/10.1503/ cmaj.211570/tab-related-content) and normal leukocyte count. A direct Coombs test was anti-C3 positive and cold agglutinin titre was 1:8192 (normal < 64) at 4°C. Screening for infectious mononucleosis, Mycoplasma pneumoniae, syphilis, antinuclear antibodies, autoantibodies and cryoglobulin was negative. Whole-body computed tomography was normal. We diagnosed cold agglutinin disease and referred the patient to hematology. Seven days later, his left fourth fingertip appeared necrotic (Figure 1B). Because neither revascularization nor surgery was indicated, the patient was instructed to avoid exposure to cold and keep warm, and the finger healed. At 12-months’ follow-up, having avoided cold exposures only, he had no new lesions or progression of anemia.
NSTL
Cma-Canadian Medical Assoc
