MSFinals-2586

MSFinals-2586

A 25-year-old man presents with a complaint of painful hands. He reports that his fingers turn white and become numb when exposed to cold, and then turn blue upon rewarming. His medical history is unremarkable, and he works in construction. On examination, there is no evidence of digital ulcers, calcinosis, chilblains, rash, or arthralgia. His blood results show a hemoglobin level of 145 g/L, platelet count of 260 * 109/L, WBC count of 6.2 * 109/L, and ESR of 10mm/hr. What is the most likely cause of his symptoms?