Multifocal thrombosis with peripheral gangrene in a young boy: Mycoplasma infection triggered cold agglutinin disease.

Cold agglutinin disease (CAD) is extremely rare in children. We report an 8-year-old boy who presented with gangrene of right foot with hypertension and absent lower limb pulses. Blood peripheral smear evidence of autoagglutination and falsely elevated red blood cell indices were suggestive of CAD and on subsequent investigations he was found to have high titres of cold agglutinin antibodies. He also had evidence of pneumonia on chest X-ray and serology for mycoplasma was positive. Computed tomography angiography showed multifocal thrombotic occlusion in bilateral popliteal arteries. He was effectively managed using antimicrobials, warm clothing, aspirin, anticoagulation and corticosteroids. He remains clinically well on follow-up and had no recurrence. CAD presenting with peripheral gangrene is extremely unusual. A careful look at peripheral blood smear gives an initial diagnostic clue. CAD triggered by infection is often self-limiting and requires supportive care.