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A5475 - TB, or Not TB: That Is the Question
Author Block: V. Murugesan, J. Tran, M. Veluru, M. Connelly; Internal Medicine, Medstar Washington Hospital Center, Washington, DC, United States.
Introduction: Tree-in-bud appearance on a chest computed tomogram (CT) represents a broad differential including infective bronchiolitis, congenital disorders, connective tissue diseases, inflammatory bronchiolitis and neoplasms with hematogenous seeding. In an immunocompromised individual the focus shifts toward infectious etiologies with mycobacterial tuberculosis as the top differential. However, atypical mycobacterial infections and fungal pneumonias must be ruled out. Case report: 32-year-old male, a recent immigrant from El Salvador 2 years ago, presented with a 5-day history of fever, cough, chest pain and 30 lbs weight loss in the last 6 months. Further testing revealed HIV infection with a CD4 count of 64. Chest X-ray was notable for an interstitial nodular pattern and a follow up Chest CT with contrast revealed numerous tree-in-bud nodules ranging in size from 2 to 11 mm with symmetric hilar and mediastinal lymphadenopathy. The patient underwent an extensive workup including sputum stain for acid-fast bacilli and pneumocystis stain, serum Interferon-gamma release assay, serum cryptococcus antigen and urine histoplasmosis antigen, all of which were negative. The patient was empirically started on anti-tuberculous therapy given the similarity to miliary pattern and a high index of suspicion. Given the lack of clear diagnosis, further investigation with bronchoscopy and bronchoalveolar lavage (BAL) was performed. The lavage fluid was notable for lymphocyte predominance cells and was positive for Pneumocystis Jiroveci organisms identified by Giemsa stain. The patient was diagnosed with pneumocystis pneumonia and started on treatment with TMP-SMX. Discussion: Pneumocystis Jiroveci pneumonia is a leading cause of respiratory infection in immunosuppressed individuals. The typical radiographic findings are bilateral diffuse infiltrates with a ground-glass appearance on CT, which is virtually diagnostic of PCP. However, less common radiographic manifestations have been reported, including lobar infiltrates, cystic lung disease, and nodular lesions. The nodules can vary from miliary to several cm lesions in size. Sputum for Giemsa stains have a highly variable sensitivity as compared to BAL which has a diagnostic yield of 90 to 100 percent in HIV-infected patients. There have been few cases reports of military pattern PCP identified in patients with AIDS or renal transplant patients. Most cases were diagnosed by either bronchoscopy or open lung biopsy demonstrating the organism by smear. Although miliary pattern on imaging studies in HIV infected individuals is highly suspicious for tuberculosis, patients should also be investigated for more common but rarer manifestations of opportunistic infections that commonly affect this sub-population.