A 29-year-old African American woman is being evaluated for exertional dyspnea and dry cough. She has no significant medical history and takes no medications. The patient works part-time as a bird keeper at a zoo. Chest x-ray reveals bilateral hilar adenopathy and reticular pulmonary infiltrates. Serum ACE levels and calcium levels are elevated. Purified protein derivative testing is negative. A bronchoscopy is scheduled to help determine the diagnosis. Which of the following is most likely to be the predominant cell type in this patient's bronchoalveolar lavage fluid?

Question

A 29-year-old African American woman is being evaluated for exertional dyspnea and dry cough.  She has no significant medical history and takes no medications.  The patient works part-time as a bird keeper at a zoo.  Chest x-ray reveals bilateral hilar adenopathy and reticular pulmonary infiltrates.  Serum ACE levels and calcium levels are elevated.  Purified protein derivative testing is negative.  A bronchoscopy is scheduled to help determine the diagnosis.  Which of the following is most likely to be the predominant cell type in this patient's bronchoalveolar lavage fluid?

Quizplus · Accepted Answer

11ec160b_3a1c_57ff_9249_b5c4ecf50c95_MD0001_00 This patient's hilar adenopathy, hypercalcemia, and elevated ACE levels are suggestive of sarcoidosis, a condition characterized histologically by noncaseating granulomas composed of activated macrophages and T lymphocytes. Activated macrophages can ectopically produce ACE and 1-alpha-hydroxylase (increases production of 1,25-dihydroxycholecalciferol, the active form of vitamin D). This results in high ACE levels and hypercalcemia commonly seen in patients with sarcoidosis. Any organ can be affected; however, the lungs (interstitial lung disease), lymph nodes (hilar adenopathy), skin (nodular rash), and eyes (anterior uveitis) are most commonly involved. Sarcoidosis may resemble other interstitial lung diseases (eg, hypersensitivity pneumonitis, cryptogenic organizing pneumonia). In such cases, quantification of the CD4⁺/CD8⁺ ratio in bronchoalveolar lavage (BAL) fluid may help in determining the diagnosis. Sarcoidosis is a CD4⁺ T-cell-mediated disease in which large amounts of CD4⁺ lymphocytes release interferon-gamma and TNF-alpha to drive macrophage activation and granuloma formation. Therefore, the BAL fluid in patients with pulmonary sarcoidosis demonstrates a lymphocytic predominance with a high CD4⁺/CD8⁺ ratio (>2:1). (Choice B) CD8⁺ cells predominate in the BAL fluid of patients with hypersensitivity pneumonitis. Although this patient has an exposure risk for hypersensitivity pneumonitis (bird handling), her hilar adenopathy as well as elevated serum calcium and ACE levels make sarcoidosis more likely. (Choice C) CD19, CD20, and CD22 are markers for the B-cell lineage. Precursor B-cell lymphoblastic leukemia (CD22⁺) may sometimes involve the pleura or present as diffuse, patchy pulmonary infiltrates. In such cases, the BAL fluid might contain CD22⁺ lymphocytes; however, elevated ACE and calcium levels suggest sarcoidosis. (Choice D) BAL fluid eosinophilia is found in eosinophilic pneumonias and tropical pulmonary eosinophilia. Although patients with hypersensitivity pneumonitis may have elevations in circulating eosinophils, they do not have elevated eosinophil counts in their BAL fluid. (Choice E) Even though the quantity of mast cells in BAL fluid may be elevated in various pulmonary diseases, there are few, if any, conditions reported to have a predominance of such cells. (Choice F) Neutrophils would predominate in patients with bacterial pneumonias. Educational objective: Sarcoidosis is a CD4⁺ T-cell mediated disease, in which large numbers of CD4⁺ lymphocytes release interferon-gamma and tumor necrosis factor-alpha to drive macrophage activation and granuloma formation. Bronchoalveolar lavage fluid in pulmonary sarcoidosis demonstrates a lymphocytic predominance with a high CD4⁺/CD8⁺ ratio.

A 29-Year-Old African American Woman Is Being Evaluated for Exertional