Woman with blue thumb

A previously healthy 86-year-old woman presented to the ED with sudden-onset pain and bruising in her left thumb, beginning several hours before. She denied any history of trauma or cold exposure. Her vital signs were stable. Physical examination revealed a subcutaneous haematoma and swelling with a normal sensation. D-dimer levels were not elevated (figure 1). Figure 1 Bruising of the left thumb on admission. What is …