system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 69-yrs-old man with a 60 pack-year history for smoking presents with dizziness and visual disturbances. Physical examination reveals a purplish discoloration of his face, arms, and neck; retinal vein engorgement; and visible distention of his neck veins. His complete blood count reveals a normocytic anemia. The pathophysiology of this patient’s clinical presentation most likely involves.
assistant
The correct answer is  The patient has the superior vena caval syndrome (SVCS). Malignancy accounts for 80% to 90% of cases of SVCS. Most cases are caused by a primary lung cancer extending into the neck and obstructing the superior vena cava. Clinically, patients have a puffy face with a blue to purple discoloration of the face, arms, and shoulders. Retinal vein engorgement results from increased venous pressure. Central nervous sys­tem findings include dizziness, convulsions, and visual disturbances. Increased venous pressure is noted in the upper extremities. The diagnosis is confirmed by venography, and the prognosis is poor.