A 23-year-old man comes to the physician because of a 6 month history of weight loss and poor energy. He also complains of vague abdominal discomfort, soft stools, and chronic back pain. He has had frequent episodes of bronchitis, which he attributes to smoking since an early age. He has had several male sexual partners over the past 3 years and has used condoms inconsistently. He was diagnosed with HIV infection six months ago, and his CD4 count at that time was 650 cells/µL.
On physical examination, scattered rhonchi are heard over the right upper lung. The abdomen is mildly tender in the epigastrium. There is no hepatomegaly and the spleen is not palpable. There are no skin rashes.
Laboratory results are as follows:
CT scan of the chest and abdomen demonstrates right upper lobe bronchiectasis with some surrounding fibrotic changes and pancreatic calcifications with atrophy.
Which of the following is most likely to establish the diagnosis in this patient?

Question

A 23-year-old man comes to the physician because of a 6 month history of weight loss and poor energy.  He also complains of vague abdominal discomfort, soft stools, and chronic back pain.  He has had frequent episodes of bronchitis, which he attributes to smoking since an early age.  He has had several male sexual partners over the past 3 years and has used condoms inconsistently.  He was diagnosed with HIV infection six months ago, and his CD4 count at that time was 650 cells/µL.
On physical examination, scattered rhonchi are heard over the right upper lung.  The abdomen is mildly tender in the epigastrium.  There is no hepatomegaly and the spleen is not palpable.  There are no skin rashes.
Laboratory results are as follows:
 CT scan of the chest and abdomen demonstrates right upper lobe bronchiectasis with some surrounding fibrotic changes and pancreatic calcifications with atrophy.
Which of the following is most likely to establish the diagnosis in this patient?

Quizplus · Accepted Answer

11ec193a_98ce_cd30_853d_17001e5b08f9_MD0002_00 This patient's clinical presentation is suggestive of cystic fibrosis (CF). Cystic fibrosis is generally diagnosed in infants and children, but approximately 7% of patients are diagnosed after 18 years of age. Adult CF patients usually present with chronic respiratory problems often labeled as asthma, COPD, and recurrent bronchitis. Adults have milder lung disease with fewer pseudomonal infections than children and usually present with upper lobe bronchiectasis, recurrent pancreatitis, chronic sinusitis, or infertility (usually due to congenital absence of the vas deferens). Adult CF patients also tend to have nontuberculous mycobacterial infections, pancreatic insufficiency, and unusual genetic mutations. Diagnosis is confirmed by sweat chloride test > 60 mmol/L on > 2 occasions, but adults may have equivocal results. Patients suspected of having CF with a normal or borderline sweat chloride test should then have a CFTR mutation analysis. Continued CF suspicion in patients without two CFTR mutations may require further workup with expanded DNA analysis or nasal potential difference measurement. This patient has upper lobe bronchiectasis with evidence of pancreatic insufficiency and should have a sweat chloride test for CF evaluation. (Choice A) A bone marrow biopsy would diagnose invasive bone marrow infections or malignancy. However, this patient's normal cell counts make this unlikely, and his presentation is more suggestive of cystic fibrosis. (Choice B) Allergic bronchopulmonary aspergillosis (ABPA) usually presents with moderate to severe persistent asthma, central bronchiectasis, elevated serum IgE, eosinophilia, and positive sputum cultures for Aspergillus species. Although up to 10% of CF patients can develop ABPA, this patient should first have a sweat chloride test to diagnose CF before further testing. (Choice C and D) Common variable immunodeficiency can present in adults with repeated sinopulmonary infections or bronchiectasis. Fungal and tuberculous infections can also cause bronchiectasis. However, given the patient's pancreatic insufficiency, he should first be evaluated for cystic fibrosis. Educational objective: Adult cystic fibrosis (CF) patients usually present with chronic respiratory tract infections, unexplained upper lobe bronchiectasis, congenital bilateral absence of the vas deferens, and/or pancreatitis. Nearly 7% of CF patients are diagnosed after 18 years of age, and sweat chloride test helps confirm CF in suspected patients. Patients with suspected CF and negative or equivocal tests should undergo further testing with DNA analysis and/or nasal potential difference measurement. __________ References: Clinical manifestations of cystic fibrosis among patients with diagnosis in adulthood (http://www.ncbi.nlm.nih.gov/pubmed/15486385) Manifestations of cystic fibrosis diagnosed in adulthood. (http://www.ncbi.nlm.nih.gov/pubmed/16217177) The diagnosis of cystic fibrosis: A consensus statement (http://www.ncbi.nlm.nih.gov/pubmed/9580754)

A 23-Year-Old Man Comes to the Physician Because of a 6