A patient with systemic lupus erythematosus (SLE) demonstrates a positive antinuclear antibody (ANA) test and elevated levels of anti-double-stranded DNA (anti-dsDNA) antibodies. Which of the following mechanisms is most likely responsible for the production of these autoantibodies?

Correct Answer: A

Rationale: The development of autoantibodies such as antinuclear antibodies (ANA) and anti-double-stranded DNA (anti-dsDNA) antibodies in systemic lupus erythematosus (SLE) is primarily attributed to a loss of self-tolerance. Self-tolerance refers to the immune system's ability to recognize and differentiate self-antigens from foreign antigens. In individuals with SLE, there is a breakdown in immune tolerance mechanisms, leading to the production of autoantibodies against self-antigens like nuclear components (e.g., DNA, RNA, histones). This loss of self-tolerance results in the immune system targeting and attacking its tissues, leading to the systemic inflammation and tissue damage characteristic of SLE. The presence of elevated levels of ANA and anti-dsDNA antibodies in this patient suggests an autoimmune response against nuclear material, further supporting the role of self-tolerance breakdown in SLE

Correct Answer: A

Rationale: In a patient with suspected pulmonary TB, the most appropriate diagnostic test for confirming the diagnosis is the sputum acid-fast bacilli (AFB) smear and culture. This test involves examining sputum samples under the microscope for the presence of acid-fast bacilli, which are characteristic of Mycobacterium tuberculosis, the bacteria that causes TB. Additionally, culturing the sputum allows for the bacteria to grow in a controlled environment, further confirming the diagnosis. In the given scenario, the patient's symptoms (cough, weight loss, night sweats, hemoptysis), along with chest X-ray findings of upper lobe infiltrates and cavitation, are highly suggestive of pulmonary TB. Therefore, performing a sputum AFB smear and culture is crucial for definitive diagnosis and initiation of appropriate treatment. The other options (Tuberculin skin test, Interferon

Correct Answer: A

Rationale: The patient's presentation with fatigue, pallor, dyspnea on exertion, low hemoglobin level, decreased MCV, and decreased MCHC are all consistent with iron deficiency anemia. Iron deficiency anemia is the most common type of anemia and occurs when there is insufficient iron available for hemoglobin production. The low hemoglobin level results in symptoms such as fatigue and pallor, while the decreased MCV and MCHC indicate microcytic and hypochromic red blood cells, respectively, which are characteristic of iron deficiency anemia. Vitamin B12 deficiency anemia and thalassemia typically present with a different pattern of laboratory findings and clinical manifestations. Sickle cell anemia is characterized by sickle-shaped red blood cells due to a genetic mutation, and the laboratory findings in sickle cell anemia are different from those seen in the patient described in this scenario.

Correct Answer: D

Rationale: The patient is presenting with symptoms and laboratory findings consistent with a paraneoplastic syndrome related to Hodgkin lymphoma. In this case, the fever, chills, generalized malaise, pancytopenia, circulating Reed-Sternberg cells, and bone marrow involvement are all indicative of a paraneoplastic syndrome associated with Hodgkin lymphoma. Paraneoplastic syndromes are a group of disorders that are triggered by an abnormal immune response to a neoplasm, such as Hodgkin lymphoma, leading to various systemic manifestations.

Correct Answer: B

Rationale: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder that leads to hemolytic anemia in response to oxidative stress. The patient's presentation of fatigue, weakness, and jaundice along with laboratory findings of hemolytic anemia (evidenced by schistocytes), elevated LDH, and decreased haptoglobin are all characteristic of G6PD deficiency. The oxidative stress causes red blood cell destruction, resulting in the release of LDH and bilirubin, leading to jaundice. Decreased haptoglobin is seen due to its consumption in binding free hemoglobin released from the lysed red blood cells. Additionally, the presence of schistocytes on a peripheral blood smear is indicative of red blood cell fragmentation, a common finding in hemolytic anemias including G6PD deficiency