Which of the following statements best describes rheumatoid arthritis?

A. Acidosis depresses respirations: While acidosis can affect the respiratory drive, it is not the primary cause of hypoxemia in pneumonia. William’s low PO2 is due to impaired gas exchange rather than depressed ventilatory effort.

B. Oxygen diffusion is impaired by the congestion: In pneumonia, alveoli fill with inflammatory exudate, mucus, and cellular debris. This fluid buildup creates a barrier to oxygen diffusion from the alveoli into the pulmonary capillaries, resulting in hypoxemia and low arterial PO2.

C. Infection reduces the effectiveness of the heart: Cardiac function may be influenced by systemic infection, but William’s hypoxemia is primarily pulmonary in origin. The heart’s pumping ability does not directly explain decreased oxygenation in the alveoli.

D. Inflammatory exudates absorb oxygen from alveolar air: Exudates do not actively consume oxygen. Instead, they physically block gas exchange by filling alveolar spaces. The impaired diffusion, rather than absorption by exudates, leads to low oxygen levels in the blood.

A. Epstein-Barr virus: Epstein-Barr virus is a viral infection that can cause mononucleosis and is associated with certain lymphomas, but it is not a cancer itself. Screening for a virus does not directly address the patient’s presentation of painless lymphadenopathy with systemic symptoms.

B. Hodgkin's lymphoma: Painless, enlarged cervical lymph nodes along with constitutional “B” symptoms such as night sweats and unexplained weight loss are classic indicators of Hodgkin’s lymphoma. These findings warrant further diagnostic evaluation, including imaging and biopsy, to confirm the disease.

C. Acute leukemia: Acute leukemia typically presents with anemia, thrombocytopenia, or infections due to bone marrow involvement rather than isolated painless lymphadenopathy. Night sweats and weight loss alone are not specific indicators for acute leukemia.

D. Burkitt's lymphoma: Burkitt’s lymphoma is a highly aggressive B-cell lymphoma often associated with jaw or facial swelling, particularly in children, and may be linked to Epstein-Barr virus. The presentation in an older adult with cervical lymphadenopathy and systemic symptoms is more consistent with Hodgkin’s lymphoma than Burkitt’s.