Suspected thermal amplitude of cryoglobulin likely more clinically significant than size detected: A case report

Cryoglobulins are proteins that are temperature sensitive, precipitating at temperatures below 37°C, and dissolve upon rewarming. However, at lower temperatures cryoglobulins can result in damage subsequently leading to vascular compromise. We present a case of a patient with a known lymphoplasmacytic lymphoma. The patient developed extensive finger necrosis and toe necrosis. Cryoglobulin was requested and a small type I was found. Given how common type I cryoglobulins are, more evidence was needed that this was the underlying aetiology of the necrosis. A biopsy of the tissue immediately proximal to the necrosis was performed. Histological evaluation confirmed cryoglobulin occlusions. Given the small cryoglobulin level, we assume the thermal amplitude of this resulted in this degree of vascular damage. Thermal amplitude of cryoglobulins is not generally performed. However, we know from testing the thermal amplitude of the red cell agglutination that the more active the antibody is at higher temperatures like those experienced in both the central and peripheral circulation, the more clinically significant the haemolysis. As this lady had chronic stable haemolysis, we sent the sample to the red cell reference lab to investigate the thermal range of the red cell antibody. This was checked at 4°C, room temperature, and 37°C. The cold antibody titre was 65536 at 4°C, 2048 at room temperature, and 1 at 37°C. This activity, despite having large titres at the cold range, demonstrated a wide thermal amplitude. Therefore, given these findings it is likely that the cryoprecipitate within the plasma had a similarly high thermal range.