Monoclonal gammopathy of undetermined significance associated with blue finger syndrome.

An 86-year-old Caucasian woman with a medical history of monoclonal gammopathy of undetermined significance (MGUS) was admitted to the hospital with a chief complaint of sudden onset of bluish discolouration of the fifth left hand digit. On a physical examination, cyanosis of the fifth digit of the left hand was noticed with decreased capillary fill but no ulcers. The patient had no tenderness on palpation. Pulses were palpable over the radial arteries bilaterally. Patients with MGUS may be at increased risk of thromboembolic disease. A clear explanation for this association in these patients is not currently known. This case report highlights the association between MGUS and thromboembolic events, particularly blue finger syndrome.