This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
[{'content': "A 2O year-old woman presents with bilateral conductive deafness, palpable purpura on the legs and hemoptysis. Radiograph of the chest shows a thin-walled cavity in left lower zone. Investigations reveal total leukocyte count 12,000/mm red cell casts in the urine and 12,000/mm serum creatinine 3 ing/dL .What is the most probable diagnosis? \nSelect and explain. \nA. Henoch-Schonlein purpura, B. Polyaeritis nodosa, C. Wegener's granulomatosis, D. Disseminated tuberculosis", 'role': 'user'}, {'content': "Answer: C \nExplanation: Granulomatosis with polyangiitis (formerly known as Wegener's granulomatosis) is characterised by granuloma formation, mainly affecting the nasal passages, airways and kidney. A minority of patients present with glomerulonephritis. The most common presentation of granulomatosis with polyangiitis is with epistaxis, nasal crusting and sinusitis, but haemoptysis and mucosal ulceration may also occur. Deafness may be a feature due to inner ear involvement, and proptosis may occur because of inflammation of the retro-orbital tissue. This causes diplopia due to entrapment of the extra-ocular muscles, or loss of vision due to optic nerve compression. Disturbance of colour vision is an early feature of optic nerve compression. Untreated nasal disease ultimately leads to destruction of bone and cailage. Migratory pulmonary infiltrates and nodules occur in 50% of patients (as seen on high-resolution CT of lungs). Patients with granulomatosis with polyangiitis are usually proteinase-3 (PR3) antibody-positive (ELISA).Pulmonary involvement may be manifested as asymptomatic infil\x02trates or may be clinically expressed as cough, hemoptysis, dyspnea,and chest discomfo. It is present in 85-90% of patients. Endobronchialdisease, either in its active form or as a result of fibrous scarring, maylead to obstruction with atelectasis . Renal disease (77% of patients) generally dominates the clinical pic\x02ture and, if left untreated, accounts directly or indirectly for most of themoality rate in this disease. Although it may smolder in some casesas a mild glomerulitis with proteinuria, hematuria, and red blood cellcasts, it is clear that once clinically detectable renal functional impair\x02ment occurs, rapidly progressive renal failure usually ensues unlessappropriate treatment is institutedPatients with active disease usually have a leucocytosis with elevated CRP, ESR and PR3. Complement levels are usually normal or slightly elevated. Imaging of the upper airways or chest . Ref - Davidsons 23e p1041 , harrisons 20e p2578,2579", 'role': 'assistant'}]