Q. A 55-year-old male with a history of alcohol use disorder and homelessness presents to the clinic complaining of multiple symptoms. He has experienced fatigue, gum swelling, and frequent nosebleeds for the past several months. He also notes worsening joint pain in his knees and has noticed his hair taking on a coiled appearance. On examination, you observe swollen and bleeding gums, petechiae, and perifollicular hyperkeratosis. His musculoskeletal examination is remarkable for joint tenderness and subperiosteal hemorrhage. Laboratory tests reveal a normocytic anemia. Given the patient's symptoms and clinical history, which of the following diagnoses is the most likely?